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INKS 



THEIR COMPOSITION AND 
MANUFACTURE 

INCLUDING METHODS OF EXAMINATION AND 
A FULL LIST OF ENGLISH PATENTS 



BY 

C. AINSWORTH MITCHELL 

B.A.(Oxon.), #I.C. 

.AND " 

T. C. HEP WORTH 

v 



WITH 46 ILLUSTRATIONS, INCLUDING 4 PLATES 




LONDON 

CHARLES GRIFFIN & COMPANY, LTD, 
EXETER STREET, STRAND 
1904 

[All rights reserved] 



Printed by BALLANTYNE, HANSON 
London &> Edinburgh 



PREFACE 



SOME three years ago we were engaged in a scientific 
inquiry as to the composition of certain fluids used as 
writing ink. As this work led us beyond the limits 
anticipated, and to the making of many experiments not 
actually required at the time, and as there is need for a 
volume dealing adequately with the subject, we thought 
it advisable to embody the results in book form. We 
found, it is true, a few small books on ink and many 
allusions to ink-making in old volumes-and isolated papers 
in scientific journals ; but it seemed to us that the matter 
required more comprehensive treatment, and the pre- 
sent work may be regarded as an attempt to supply that 
want. 

As far as time permitted we have tested the various 
formulae quoted, but, as may be seen by reference to the 
patent list at the end of the book, there are so many cases 
of slight variations in composition that we have often 
contented ourselves with a record of the statements put 
forward. 

We have pleasure in tendering our best thanks to those 
who have assisted us in our work. 

To Mr. R. M. Prideaux, in particular, we are indebted 
for the excellent drawings of the various galls (pp. 37-46), 
the details of which could not have been nearly so w*ll 
shown by photography. 

Messrs. Newman and Co., of Soho Square, were good 
enough to afford us m uch information with regard to sepia 



vi PREFACE 

preparations, and to supply us with dried specimens, &c., 
tor analysis. 

The photographs of fossil cephalopoda were taken by 
us at the Geological Museum, Jermyn Street, by the 
courtesy of the Curator. 

To the authorities at Kew we are indebted for permis- 
sion to photograph in the Museum and in the Herbarium. 

The Badische Company kindly supplied us with specimens 
of aniline dye-stuffs and much valuable information 
regarding them. 

We have also to thank Messrs. Keller and Co., who 
have kindly allowed us to use certain blocks illustrative 
of printing-ink machinery, and have sent us samples of 
various permanent colours. 

Lastly, our thanks are due to Messrs. Madderton 
and Co., of Loughton, for specimens of permanent pre- 
parations made by them. 

C. A.M. 
T. C. H. 

GRAY'S INN, LONDON W.C. 
August 1904. 



CONTENTS 



HISTORICAL INTRODUCTION 

Ancient Egypt Old papyri Progress of writing Herculaneum frag- 
ments Carbon inks Iron gall inks The Lindisfarne Gospels 
Transition from carbon to gall inks Domestic ink making Scientific 
experiments Unoxidised gall inks Aniline inks German regula- 
tions Other inks .... . . Pages 1-14 



SECTION I 
WRITING INKS 

CHAPTER 1 

CARBON AND CARBONACEOUS INKS 

Sepia Source Manufacture Chemical composition Sepiaic acid 
British sepia Examination of commercial sepia Indian or 
Chinese Ink Lamp-black Composition Manufacture of lamp, 
black Old European methods Manufacture of Indian ink Qualities 
of Indian ink Examination of Indian ink Practical tests Carbon 
Writing Ink Ancient carbon inks Modern carbonaceous inks 

Pages 15-35 

CHAPTER II 

TANNIN MATERIALS FOR INKS 

Galls : Origin Aleppo galls Chemical composition Chinese galls 
Chemical composition Japanese galls Acorn galls Oak-apple galls 
Other galls Tannins Classification of tannins Suitability of 
tannins for ink-making Chestnut bark and wood Chestnut 
extract Chestnut tannin Ink from chestnut wood Sumach 



viii CONTENTS 

Sumach tannin Ink from sumach Divi-divi Divi-divi tannin 
Ink from divi-divi Myrobalans The tannin of myrobalans 
Valonia The tannin of valonia Ink from valonia Oak- bark 
tannins Keactions of oak tannins Amount of tannins in oak-bark 
Ink from oak-bark Gallotannic acid Fermentation of gallotan- 
nic acid Properties Reactions distinguishing between gallotannic 
and gallic acids Pages 36-71 



CHAPTER III 
NATURE OF INKS 

Constitution of ink-forming substances Influence of light and air 
Iron tannates Evidence of an intermediate blue iron oxide 
Tannates of iron Basic salts Methods of estimating tannates 
Procter's method Jackson's lead carbonate method Ruoss's ferric 
sulphate method Colorimetric methods Hinsdale's colorimetric 
method Mitchell's colorimetric method . : . Pasres 72-8(5 



CHAPTER IV 

MANUFACTURE OF IRON GALL INKS 

The relative proportion of galls and ferrous sulphate Deductions from 
the composition of ink deposits Old type of iron gall ink Old 
formulas of iron gall. inks Unoxidised iron gall inks Gallic 
acid inks Japan inks ...... Pages 87-08 



CHAPTER V 

LOGWOOD, VANADIUM, AND ANILINE BLACK INKS 

Logwood inks Logwood Logwood extract Hasrnatoxylin 
Hasmatein Iso-hcematein Addition of logwood to gall inks Log- 
wood inks without tannin Chrome logwood inks Ha?matein inks 
Use of logwood in patent inks Vanadium inks Black aniline 
inks Pages 99-111 

CHAPTER VI 

COLOURED WRITING INKS 

Historical Coloured aniline inks Fugitiveness of aniline inks 
Patented coloured inks Pages 112-118 



CONTENTS ix 

CHAPTER VII 

EXAMINATION OF WRITING INKS 

Fluidity of ink Penetration through paper Stickiness of writing 
Composition of commercial inks Schluttig and Neumann's stripe 
test Acidity, action on steel pens Stability on keeping Examina- 
tion of handwriting Old manuscripts Palimpsests Forged 
handwriting Bleaching agents Differentiation of writing done 
with different inks Photographic methods Mechanical erasure 
Chemical removal of writing Destruction of sizing Alterations and 
additions to writing Photographic distinction between different 
inks . Pages 119-131 

SECTION II 
PRINTING INKS 



CHAPTER YIII 

EARLY METHODS OF MANUFACTURE 

Historical China Greec and Rome England Early printed books 
Early methods of manufacture Fertel's method of making ink 
Breton's method Savage's method of manufacture Modern methods 
of preparing ink Pages 132-140 

CHAPTER IX 

MANUFACTURE OF VARNISH 

Boiled oils Burnt oil Varieties of lithographic varnish Andres' 
apparatus for boiling oil Apparatus with steam-jacket and air-blast 
Boiling with superheated steam Treatment with oxygen Linseed- 
oil substitutes Pages 141-150 

CHAPTER X 

PREPARATION AND INCORPORATION OF THE PIGMENT 

Black for printing ink Modern apparatus Thenius' lamp-black furnace 
Furnace for producing black from pitch Other black pigments 
Carbon blacks Purification of lamp-black Composition of lamp- 
blacksMethods of examining lamp-blacks and gas-blacks 
Mixing the black and varnish Mixing the varnish and lamp- 



CONTENTS 

black Quack's mixing machine Werner and Pfleiderer's mixing 
machine Lehtnann's mixing machine Grinding Lehmann's 
grinding machines Machines by Neil, Jackson, Kingdon Litho- 
graphic printing ink Collotype ink . . . Pages 151-166 



CHAPTER XI 
COLOURED PRINTING INKS 

Early methods Manufactured inks Painters' pigments Early gnor- 
ance as to proper pigments Half-tone process block Necessity for 
cleanliness Overlays Coarse-grain screens Theory of colour 
Diagrams of colour Peculiarities of pigments Permanency of 
pigments Yellow pigments Red pigments Blue pigments Green 
pigments Purple and orange pigments Brown pigments " Art " 
shades Three-colour printing Photographic falsification of 
colour Coloured screens Clerk-Maxwell's work Colour screens or 
niters Coloured light Pure pigments unknown General considera- 
tions Examination of trichromatic prints The half-tone dot 
Necessity for transparent inks Opacity of yellow pigments Supple- 
mentary key block Inks for cheques and bank-notes Patent 
inks for cheques ..,...., Pages 167-185 



SECTION III 
INKS FOR MISCELLANEOUS PURPOSES 

CHAPTER XII 

COPYING INKS 

Various copying inks Patent copying inks Copying papers Copying 
ink pencils Manifold copying apparatus . . Pages 186-191 

CHAPTER XIII 

MARKING INKS 

The ink plant of New Granada The Indian marking nut The Cashew 
nut Rhus toxicodendron Rhus venenata Rhus radicans Other 
vegetable juices Chemical marking inks Silver inks Gold 
marking inks Platinum marking inks Marking inks containing 
other metals Aniline marking inks Indigotin marking inks 
Alizarine marking ink Examination of marking ink Marking-ink 
pencils Pages 192-206 



CONTENTS xi 

CHAPTER XIV 

SAFETY INKS AND PAPERS 

Various safety inks Resinous inks Traill's carbon gluten ink 
Soluble glass ink Other carbon inks Safety papers with special 
inks Patent permanent inks Patent safety papers 

Pages 207-213 

CHAPTER XV 
SYMPATHETIC INKS 

History Various sympathetic inks Patent sympathetic inks 

Pages 214-218 

CHAPTER XVI 

INKS FOR SPECIAL PURPOSES 

Ink powders and tablets Logwood ink powders Aniline ink powders 
Patent ink powders and dried inks Stencil inks Show-card ink 
Inks for rubber stamps Inks for writing on glass Hydro- 
fluoric inks Resin inks Foertsch's pencil for glass Inks for 
writing on metals Ink for writing on leather Ink for ivory 
surfaces Ink for writing on wood Fireproof inks 

Pages 219-22C. 

LIST OF ENGLISH PATENTS . . . . Pages 227-242 
INDEX . . . . . Pages 243-251 



LIST OF ILLUSTRATIONS 

Frontispiece Elizabethan housewife's recipe 

FIG. PAGE 

1 Egyptian palette, brushes and pens 6 

2 Egyptian slab and muller . . . . . . .6 

3 Egyptian wax tablet 6 

4 Common cuttlefish (Sepia officinalis) . ... 16 

5 Fossil sepia 17 

6 Fossil sepia 18 

7 Dried sepia sacs 21 

8 Chinese manufacture of lamp-black . 24 

9 Chinese manufacture of ink ... 25 

10 European lamp-black chamber 27 

Brush drawing in Chinese ink by Japanese artist (Plate I.) 

To face 30 

11 English double oak-apple gall . .... 37 

12 English oak gall 37 

13 English gall 37 

14 Green Aleppo gall 38 

15 White Aleppo gall 38 

16 Section of white gall '38 

17 Chinese gall 41 

18 Japanese gall ... 44: 

19 Aphis from Chinese gall 45 

20 Aphis from Japanese gall 45 

21 Oak-apple gall 46 

22 Gall wasp (Cynips Kollari] 47 

23 Sumach (Coriaria myrtifolia) ...... 55 

24 Divi-divi pods 58 

25 Myrobalans 59 

26 Valonia 61 

27 Trimble's apparatus for tannin determination ... 81 



xiv LIST OF ILLUSTRATIONS 



FIG 



PAGE 

28 Hehner's Nesslerising tubes . . . . . '. 8(5 

29 Action of bleaching reagents on writing (Plate II.) To face 129 

30 Free-fired pan for boiling oil 143 

31 Andres' apparatus Ho 

32 Steam-heated kettles U 

33 Apparatus for hot-air treatment of oils ... 147 

34 Lamp-black apparatus .152 

35 Lamp-black apparatus .153 

36 Quack's mixing machine . . V lfi<) 

37 Lehmann's mixing machine 1(H 

38 Lehmann's grinding mill . . . . . . Ifi'J 

39 Colour diagram . . .171 

40 Solar spectrum in triplicate (Plate III.) . . . To face 17S 

41 Clerk-Maxwell's colour curves 180 

42 Indian marking ink (Sf-nief&rpUQ anacareliuin) . . . 193 

43 Cashew nut (Anaeardin m Occident tile] ..... 195 

44 Rhiis toxicodendron . ' . 197 



HISTOEICAL INTRODUCTION. 

CONTENTS. Ancient Egypt Old papyri Progress of writing 
Herculaneum fragments Carbon inks Iron gall inks The 
Lindisfarne Gospels Transition from carbon to gall inks 
Domestic ink-making Scientific experiments Unoxidised gall 
inks Aniline inks German regulations Other inks. 

Ancient Egypt. The earliest use of a liquid which can 
be described as "ink" is found in those documents on 
papyrus which have been among the archaeological 
treasures of Egypt. Although the history of Egypt has 
been traced back for a period of more than four thousand 
years, and papyrus was employed as a writing material 
there from very remote times, the oldest specimen of the 
material extant is a roll which dates from B.C. 2500.* This 
possibly refers to the oldest specimen which bears decipher- 
able characters, for Professor Flinders Petrie has found 
fragments of papyri which date from a thousand years 
earlier.f As Egypt is still the subject of exploration, and 
as perishable articles have been found of a still earlier period 
than that last mentioned, we may reasonably hope that 
ink- written records may some day come to light which will 
carry back the history of the country to a more remote 
time. Professor Flinders Petrie found in one tomb, dating* 
from 3500 B.C., baskets, a coil of palm rope, wooden 
mallets, and chisels left behind by the workmen, together 
with some pieces of papyrus which were almost white ; and 
he attributes the excellent condition of these things to the 
preservative nature of the clean dry sand in which they 
had been buried for so many centuries.} 

* British Museum- Guide, 1896, p. 312. 
t Journal of the Camera Club, Nov. 1897. 
I Ibid, 



MANUFACTURE 

Old Papyri. In Case A (Greek Papyri), British Museum, 
can be seen a number of specimens dating from the first 
century of the Christian era, and although in many cases 
* V the papyrus is merely in fragments, the ink is as black as 
it was the day that it was applied. The lettering in many 
of these papyri is extremely beautiful, and compares very 
favourably with much of the handwriting that some of us 
have to decipher to-day. And it would seem quite clear 
from an examination of many of these writings that the 
implement employed was a pen and not a brush. The 
papyrus in some instances is of a very light drab colour, 
and on this surface the old writing stands out with startling 
distinctness ; but when the material has assumed a dark 
brown or yellow tint, the writing is not so distinct, although 
the quality of the ink is quite as good. 

That papyrus was not a cheap material is- shown by a 
specimen here, labelled " Aristotle on the Constitution of 
Athens. The only extant MS. of the work, brought from 
Egypt in 1890. Written about A.D. 100, ia four rolls, in 
four different hands, on the back of the papyrus which 
had already been u?ed [in A.D. 78-79] for the acconipts of 
a farm-bailiff named Didymus, near Hermopolis." 

Another specimen of great interest lies close to the one 
first mentioned, namely, fragments of the Theogonia of 
Hesiod. It is written in a firm and large hand in very 
black ink, and the label tells us that its date is probably the 
fourth or fifth century, " contemporary with the early MSS. 
on vellum, and so marking the transition from the one 
material to the other." 

Progress of Writing. The various specimens shown in 
the King's Library at the British Museum, in Cases A E, 
are designed to illustrate the progress of writing from the 
second century B.C. to the fifteenth century of our era, and 
at the same time they afford testimony as to the kind of 
ink employed during the period covered. The basis of 
the black ink used on papyrus by the ancient scribes was 
undoubtedly carbon, a substance which had the advantage 
of being easily procurable, while at the same time it was 
indestructible except by fire. It was probably prepared in 
the form of vegetable or animal charcoal, and was mixed 
with gum, oil, or varnish. Possibly, for the finer writing, 



HISTORICAL INTRODUCTION 3 

water, with gum or glue as a binding material, was the 
medium mostly employed, for it would flow more readily 
from the reed pen or quill used by the writer. 

It is certain that the art of writing has a remote 
antiquity, and that the power of recording thoughts in 
this way marks a distinct line of demarcation between 
civilised man and the savage. J t is a matter of interest to 
consider the many different materials which have been 
used for writing upon in early times besides papyrus. Soft 
wood cut into slices and planed and polished was used in 
various countries, the pen being a metal stylus, which 
simply scratched or indented the material. ~l7ater on, the 
wood tablet with a thin coatingof wax was employed, and the 
writing upon it in the case of ephemeral memoranda could 
be quickly effaced. Bark and palm leaves were also used 
for writings of a temporary character, and in some countries 
in later times both linen and silk have been so employed. 
The Chinese are credited with the invention of paper 
anterior to the Christian era, a statement which need not 
excite surprise when we remember that they anticipated 
Europe in the invention of printing by nearly a thousand 
years. We may assume that for many centuries before 
this the art of writing in China had been brought to some 
degree of perfection. 

Among the Roman antiquities found in Britain, which 
are now deposited at the British Museum, are many speci- 
mens of the stylus in ivory, bronze, &c., and some of these 
are armed with a sharp projection, with which guiding lines 
could be ruled across the waxen surface of the tablets, 
The reed pen was commonly used for writing on papyrus, 
and the steel pen was foreshadowed by a few specimens in 
bronze found in Italy, and one in England. This last is 
among the Romano-British antiquities in the British 
Museum. It consists of a tubular piece of bronze, about 
five inches in length, which has at one end a split nib, while 
the tube is gradually reduced in size towards the other 
extremity, where it ends in a solid piece, which was probably 
used for pressing down the wax in order to efface the 
writing. 

In the Mediaeval Room at the British Museum may be 
found many specimens of writing tablets, some dating 



4 INKS AND THEIR MANUFACTURE 

before the seventh century, of great rarity and therefore 
great value. Some of these are what is known as "con- 
sular diptychs," so-called because these folded tablets were 
at one time sent as ceremonial presents by the Roman 
consuls on their appointment to official persons or to friends. 
Many of these tablets are of ivory and are beautifully 
carved, and the slabs or plaques are sometimes of such a 
size that the tusks procurable at the time they were made 
must have been of unusual dimensions, or the artificers 
had some means of bending the material, the secret of 
which is now lost. 

Herculaneum Fragments. In 1821 Sir Hiaiqrfiry Davy 
read a paper before the Royal Institution,* in which he 
described a number of experiments that he made with 
some fragments of papyri which had been found in the 
ruins of Herculaneum. Of some of these papyri he says : 
"The black ones, which easily unroll, probably remained 
in a moist state without any percolation of water ; and the 
dense ones, containing earthy matter, had probably been 
acted upon by warm water, which not only carried into the 
folds earthy matter suspended in it, but likewise dissolved 
the starch and gluten used in preparing the papyrus and 
glue of the ink, and distributed them through the sub- 
stance of the MSS." 

He made further experiments in the Museum at Naples. 
And of some of the MSS. he says : " These MSS. had been 
so penetrated by water that there were only a few folds 
which contained words, and the letters were generally 
erased, and the charcoal which had composed them was 
deposited in the folds of the MSS." 

He makes some general observations, of which the fol- 
lowing is worth noting : 

" I looked in vain amongst the MSS. and on the animal 
(sic) charcoal surrounding them for vestiges of letters in 
oxide of iron ; and it would seeni from these circumstances, 
as well as from the omission of any mention of such a sub- 
stance by Pliny, that the Romans, up to his period, never 
used the ink of galls and iron for writing : and it is very 
probable that the adoption of this ink, and the use of 
parchment, took place at the same time. For the ink, 

* Trans. Roy. Soc., 1821, ii. 191. 



HISTORICAL INTRODUCTION 5 

composed of charcoal and solution of glue, can scarcely 
be made to adhere to skin r ; whereas the free acid of 
the chemical ink partly dissolves the gelatine of the 
MSS., and the whole substance adheres as a mordant ; 
and in some old parchments, the ink of which must 
have contained much free acid, the letters have, as it 
were, eaten through the skin, the effect being always 
most violent on the side of the parchment containing no 
animal oil.''* 

The disintegration of the papyrus by the action of 
water, alluded to by Sir Humphry Davy,^ will be readily 
understood when we remember that this ancient writing 
material was made of thin strips cut from the reed and 
cemented together. The strips were laid side by side, and 
then other strips were laid across them at right angles, the 
whole being stuck together and placed under pressure so 
as to form a paper-like sheet. Papyrus was first used as a 
single sheet, or in lengthy documents as a long roll of 
different sheets joined together. Later on papyrus leaves 
were bound together as in a book. At a very early period 
papyrus was imported into Greece and Italy. It continued 
to be the chief writing material in Egypt until the tenth 
century, and was largely used in Europe after vellum had 
been introduced. 

Carbon Inks. We give illustrations (Figs. I, 2, and 
3) of various writing implements dating back to about 
1500 B.C., which are exhibited in the Egyptian department 
of the British Museum. The titles of these pictures 
sufficiently explain their nature. 

Chinese, or Indian ink, as it is commonly called in this 
country, was made at a very early period, according to 
Chinese historians as far back as between B.C. 2697 and 
2597, the inventor being one Ticn-Trheu. Full particulars 
of the way it is manufactured are given in a subsequent 
chapter. Its base, like that of early Egyptian and other 
inks, is carbon. 

' :< Tt-fftix. Hoy. <SW-., 1821. ii. 191. 

t Several illustrations are attached to Sir H. Davy's paper, mostly 
showing fragments of papyrus with writing upon them. Fig. I shows 
an ink pot, a reed pen, and a roll of papyrus, and Fig. 2 a box contain- 
ing rolls of papyrus. 



INKS AND THEIR MANUFACTURE 




Fig. i. Egyptian palette, brushes and pens. 




Fig-. 2. Egyptian slab and inuller. 




Fig. 3. Egyptian wax tablet. 



HISTORICAL INTRODUCTION 7 

Dioscorides,* physician to Antony and Cleopatra (B.C. 
40-30), in a dissertation on the medicinal use ot herbs, 
gives the proportion of lamp-black and oil to be used in 
the manufacture of ink (atr amentum). 

Vitrumusjr the Roman engineer and architect (B.C. 30- 
A.D. 14), describes a method of preparing ink for mural 
decoration : soot from pitch-pine being collected from the 
walls of a specially constructed chamber, mixed with gum 
(glutinum)) and dried in the sun. 

Pliny\ (A.D. 23-79) mentions that writing can be readily 
sponged out, and also speaks of the different varieties of 
ink in use in his tini'). 

Martial\\ (A.D. 100) sends a sponge with his newly 
written book of poems, so that the writing could be effaced 
if the composition did not merit approval. 

It is clear from these last two references that an oil- 
carbon ink cannot be meant, for it would be impossible of 
removal with water. Either a preparation of lamp-black 
and gum must be referred to, or possibly an ink made 
from sepia. Pcrsius^ (A.D. 34-62) refers to ink becoming 
too thick and too pale on adding water, and uses the word 
" sepia." Cicero, a century earlier, refers to the use of this 
natural ink. 

Many other natural inks, but of vegetable origin, have 
been used for writing and marking in various parts of the 
world. All are fully described later on. 

Iron Gall Inks. The monk Theopliihis** who wrote an 
encyclopaedia of Christian art in the eleventh century, 
describes, among other things, a method of preparing 
writing ink from thorn wood. An aqueous extract of the 
wood was evaporated to dryness and the powder mixed 
with green vitriol. This is the earliest reference which 
we have been able to find to an iron-tannin ink. 

A treatise was published in Paris in 1393, under the 
title of Menogicr de Paris, in which a method of preparing 
an iron ink with galls was described. 

* Folio edition, 1598. in Greek and Latin. 

-j- De Architectural lib. vii. 10. J .\<tt. Hist, xxvii. 52. 

Hid. xxxv. 41. || iv. 10. ^ tiat'lres, iii. 13. 

** Theophilus, * D'.rersantm Arthun Se/iednht, lib. i. chap. xl. p. 48, 
Hendrie's translation 



8 INKS AND THEIE MANUFACTURE 

JVecker, a doctor of medicine of Basle, in 1612* de- 
scribes the preparation of an indelible ink compounded of 
lamp-black and linseed oil. He also alludes to coloured 
inks, and in particular to sympathetic inks. 

Peter- Canneparius, professor of medicine at Venice, 
wrote on inks, De Atramentis, &c. ;f and described the 
composition of various sorts of ink. Black ink is referred 
to as being made from galls and vitriol, while coloured inks 
are procured from gums, woods, the juices of plants, &c. 

Sir E. Maundc Thompson remarks* that ink differs in 
tint at various periods and in different countries, and that 
while in early MSS. it is pure black, or slightly brown, in 
the Middle Ages it varies a good deal according to age 
and locality. He also tells us that in Italy and Southern 
Europe the ink of MSS. is generally blacker than in the 
north, and that a Spanish MS. of the fourteenth or 
fifteenth century may usually be recognised by the pecu- 
liar blackness of the ink. The ink of the fifteenth century 
is often of a faded grey colour. 

The Lindisfarne G-ospels. The MS. known as The 
Lindisfarne Gospels, or The Gospels of St. Cuthbert, or The 
Durham Book, is of great interest, for it is one of the 
earliest, and certainly one of the most beautiful, MSS. on 
vellum possessed by the British Museum. Four paintings 
representing the Evangelists precede the respective Gospels, 
and three of them are shown in the act of writing. It is 
noteworthy that the pen, very plainly shown in the figure 
of St. Mark, is cut like a quill. This MS. is unusually 
fresh and clean, although according to tradition it was, 
upon one occasion, lost at sea in a violent storm, and was 
recovered at low tide by the intervention of St. Cuthbert. 
The date at which it was written is supposed to be at the 
close of the seventh century. This valuable MS. is placed 
in a case next to an MS. of Shakespeare's time ; and 
although one is nearly nine centuries older than the other, 
the ink of the earlier work is perfectly black and well 
preserved, while that of the other is very much faded. 

With regard to the later MSS. on paper and parchment, 

* De Secret is^ lib. xvii. 713. 

t London edition, 1660. 

J Greelt and Latin Paleography. 



HISTORICAL INTRODUCTION 9 

and confining our attention to those which are exhibited 
in the open cases at the British Museum, there is little to 
complain of in the quality of the ink. The writing is 
mostly of a rich dark-brown, and we may take it that if an 
MS. has thus preserved its freshness for three or four 
centuries the ink may be regarded as permanent enough 
for all practical purposes. It is interesting to note that 
in some of these MSS. two different inks have been used 
on the same page. For instance, we have here the Bible 
which belonged to Milton, on the first page of which he 
has entered in his own hand memoranda of the births of 
himself and members of his family. All the entries are 
written in a dark ink, with one exception this is the 
entry referring to the birth of his daughter Deborah on 
" the 2nd of May, being Sunday, somewhat before 3 of 
the clock in the morning, 1652." The ink in this case is 
very pale, the loss of colour being possibly due to hasty 
dilution. 

Transition from Carbon to Gall Inks. The transition 
from carbon ink to that made from galls and iron is a very 
gradual one, and we find many writers deploring the 
effects of that change. Mr. Astle* (1803) complains that 
the modern ink is not comparable with that used by the 
ancients, and attributes the deterioration to negligence in 
manufacture. He writes : " Gall-nuts, copperas, and gum 
make up the composition of our inks, whereas soot or 
ivory black was the chief ingredient in that of the 
ancients.'' 

Another paragraph from the same source is worthy of 
quotation : 

" Although paper is now chiefly made from linen rags 
beaten to a pulp in water, yet it may also be made of 
nettles, hay, straw, parsnips, turnips, colewort leaves, flax, 
or of any fibrous vegetable." 

This extract, written just a century ago, is interesting 
in view of the circumstance that linen rags are now only 
used for the very finest grades of paper. Wood pulp is 
now largely employed, and there is ground for the fear that 
in the future it will not be the quality of the ink which 

* Oriyin of Writing, 1803, p. 210. 



10 INKS AND THEIR MANUFACTURE 

will be called into question, so much as the perishing of the 
material upon which the writing is recorded. 

We may also notice here " Some Observations on 
Ancient Inks"* which formed the subject of a communi- 
cation to the Royal Society by Sir C harks Blagdcn. He 
made experiments on various MSS. on vellum, dated from 
the ninth to the fifteenth centuries. The ink of some was 
still quite black, while that of others varied from a deep 
yellowish brown to a very pale yellow. These were lent 
him by Mr. Astle. 

He made several experiments, and convinced himself 
that the ink used in these MSS. was iron-gall. " No trace 
of a black pigment of any sort was discovered." 

He attributes "the greater durability of the more 
ancient inks " to the more careful preparation of the 
parchment or vellum ; one writing only resisted all the 
agents which he employed, and that turned out subse- 
quently to be part of a very ancient printed book. 

Perhaps the change of which so many writers complain 
may be more reasonably ascribed to the want of know- 
ledge with regard to the proper proportions of the ingre- 
dients employed in the preparation of ink, which had not 
yet attained the position of an article of commerce. 

Domestic Ink-making. It is very difficult for us in 
this twentieth century to realise a time in Britain when 
the art of writing was a polite accomplishment, only 
known to a privileged few ; when the commercial manu- 
facturer of ink did not, could not exist, for he would have 
starved through lack of custom. Then it was that the 
careful housewife would rank it among her duties to make 
ink, just as she made cordials, and compounded medicines 
of marvellous origin for the family use ; and we may take 
it for granted that recipes for the manufacture of writing 
fluids, sympathetic and otherwise, would be handed down, 
with other nostrums, as precious heirlooms from genera- 
tion to generation. 

We have evidence of this in an interesting volume 
which was compilt-d a few years ago by Mr. George 
Weddell, of Newcastle-upon-Tyne.f It is a book of 

* Tran*. Roy. 8oc., 1787. Ixxvii. [ii.] 451. 
f Arcana Fairfa-riana Manuieripta, 1890. 



HISTORICAL INTRODUCTION 11 

family recipes, which came into his hands by an accident. 
He has reproduced it in fac simile, and it is certainly a 
most interesting relic of domestic life in the sixteenth and 
seventeenth centuries. It deals with all kinds of things, 
good and bad, from recipes for apple pasties to cures for 
the King's evil. And among the strangely assorted items 
we find several recipes for making ink. By the kind 
permission of Mr. Wedddl we reproduce one of these as a 
frontispiece ; and as few, possibly, of our readers will be 
able to decipher the strange calligraphy, the gist of a 
transcription which Mr. Wedddl has been good enough to 
supply, is given in chap. iv. 

Another recipe in this delightful old volume stands as 
follows : 

" Take a quart of fair spring water, one ounce of copperas, two ounces 
of gall, and four ounces of guni-arabick mingle them together and let 
them stand." 

Here is another method : 

; ' Take four ounces of gum arabick beat small, 2 ounces of gall beat 
gross. One ounce of copperas, and a quart of the comings off strong ale. 
Put all these together andstirr them 3 or 4 times a day about 14 dayes 
then strein it through a cloth." 

Then follows this note : 

" I made ink by ye above rect. only putting half ye arabick and as 
good as ever was used. K. GREEN/V 

One more recipe from the same source is as follows : 

' Mr. Mason, Exciseman, his rect. for making ink, which is very good. 

" Take a quart of rain or other soft water and put to it 4 oz. of best 
blue galls gross by beattin let it stand warm for 3 days then add 3 oz. 
of copperas 4 oz. of gum ditto roach (rock) allum let it stand 2 or 3 days 
longer but shake it up 2 or 3 times a day put a little Brandy into the ink. 
The bottlein it will hinder it from Mouldiness." 

There is no date to any of these recipes. Mr. WcddeJl, 
who has made a study of the different handwritings repro- 
duced in this book, is of opinion that the first of them, our 
frontispiece, is certainly Elizabethan, and that it was 
probably written at the end of the sixteenth century by a 
man past middle age, who learned to write just about the 
time that Shakespeare was born (1504). 

A book on handwriting by John dc Beau CHiesne and 
If. John Baildon, printed at Blackfriars in 1571, entitled 



12 INKS AND THEIR MANUFACTURE 

A JBook containing divers Sorts of Hands, contains "Rules 
made by E. J3. for his children to learne to write bye." 
They include directions for making ink. These are quaint 
enough to deserve quotation : 

'' To make common yncke of Wyne take a quarte, 
Two ounces of gomme, let that be a parte, 
Five ounces of galles, of copres* take three, 
Long standing dooth make it better to be ; 
If wyne ye. do want, rayne water is best, 
And as much stuffe as above at the least : 
If yncke be to thick, put vinegre in, 
For water dooth make the colour more dimme. 
In hast for a shift when ye have a great nede, 
Take woll, or wollen to stand you in steede ; 
Whiche burnt in the lire the powder bette small 
"With vinegre, or water make yncke with all. 
If yncke ye desire to keep long in store 
Put bay salte therein, and it will not hoare.j 
If that common yncke be not to your minde 
Some lampblack thereto with gomme water grinde." 

In 1609 an iron- gall ink was invented by Guyot, and 
sold on the Pont Neuf, Paris, under the title of cncrc dc la 
petite vcrtu.l 

Scientific Experiments. In the following century, so 
much more attention appears to have been given to the 
manufacture of writing ink, that we find a compound 
known as " the celebrated Dresden ink " being used in 
Germany. We give further details as to its composition 
in chap. iv. 

William Leivis, M.D., in 1748, has the credit of being 
the first to make writing fluids the subject of scientific 
experiment, and to draw deductions as to the best pro- 
portions of the various ingredients required to make a 
really permanent ink. 

Ribeaucourt (1/92) j| carried out experiments on the 
same lines as Lewis, but arrived at somewhat different 
conclusions as to the correct proportions of the con- 
stituents. 

* Copperas, I.e., FeS0 4 . 

t A.S. har, hoary, gray. Ice. Jiat-r. In allusion to the gray colour 
caused by mould. 

% Blondel, Les Outlh de VEcnmln^ 1890. p. 153. 

Commercivm Phitesophico-technlcum, London, 1763, p. 377. 

|| AHH. Chun., 1792, xv. 113. 



HISTORICAL INTRODUCTION 13 

Unoxidised Gall Inks. The use of dyestuflfs such as 
logwood or indigo to strengthen the colour of the ink, 
was practised to a small extent during the eighteenth 
century ; but the inks were still of one type, that is to say, 
the fluids were more or less oxidised before their applica- 
tion to the paper. In the early part of last century, 
however, a radical change came about in the method of 
manufacture, and credit for the innovation is claimed by 
the well-known firm of Stephens. Previously to this, the 
finished ink was exposed to the action of the atmosphere 
so as to darken it as much as possible, whereby it was 
rendered more or less insoluble, and would, therefore, for 
the most part, remain on the surface of the paper. The 
new process consisted in keeping the ink from oxidation 
as far as possible, so that the formation of the insoluble 
pigment would take place within the fibres of the paper ; 
at the same time indigo was added to give the fluid a 
" provisional " colour. 

An unoxidised ink of the same type was patented by 
Leonhardi in Hanover in 1856, a small proportion of 
madder being incorporated in addition to the indigo. 
Hence the term alizarine, which has been accepted as a 
descriptive title for this type of ink, although Leonhardi 
subsequently omitted the madder as being superfluous. 
Attempts to employ the more appropriate term "isatin" 
(indigo) to such inks were unsuccessful, and they are still, 
on the lucus a non lucendo principle, called '' alizarine.' 7 
Other manufacturers have seen the advantages of a non- 
oxidised ink, and blue-black writing fluids are now largely 
made. In 1891 Schluttig and Neumann examined eighty- 
one German inks, and found that all were of the new 
type the older kind of ink being obtainable from a few 
small makers. 

Aniline Inks. The next development in the manufac- 
ture of ink is found in the use of aniline dyes, not merely 
for coloured writing fluids, but also for taking the place of 
the indigo in the black inks. The first British patent for 
the employment of these dyes as ink was granted to Groc, 
of Paris, in 1861, and he was followed by several others. 
Thus, under the name of " Stylographic ink " a solution of 
nigrosine was introduced in 1867, as being specially 



14 INKS AND THEIR MANUFACTURE 

suitable, 011 account of its fluidity, for stylographs and 
fountain pens. 

In 1878, at the Paris Exposition, a medal was given to 
the makers of an aniline ink which was found capable of 
great resistance to the action of acids, alkalies, and 
chlorine. 

German Regulations. In 1879 Professor Kocstcr, of 
Bonn, wrote to the German Chancellor, pointing out the 
danger of using aniline inks for historical documents on 
account of their instability ; and, as a result of this, Prussia 
passed a law in the same year enacting that only iron-gall 
inks should be used officially. 

In 1888 rules for testing ink were published, and inks 
were classified according to the way in which they 
answered to these regulations. Some of these tests have 
been severely criticised by Schluttig and Neumann. 

Other Inks. Coloured inks, marking inks, printing- 
inks, and inks for special purposes, need only be alluded 
to, as they are fully dealt with in subsequent chapters. 
The interesting question of the detection of forgeries by 
photographic and other means is also considered at 
length. 



SECTION I. 
WRITING INKS. 

CHAPTER I. 

CARBON AND CARBONACEOUS INKS. 

CONTENTS. Sepia Source Manufacture Chemical compo- 
sition Sepiaic acid British sepia Examination of commer- 
cial sepia Indian or Chinese Ink Lamp-black Compo- 
sition Manufacture of lamp-black Old European methods 
Manufacture of Indian ink Qualities of Indian ink Examina- 
tion of Indian ink Practical tests Carbon Writing Ink 
Ancient carbon inks Modern carbonaceous inks. 

As was shown in our preliminary historical sketch, inks 
having carbon or a carbonaceous pigment in a finely divided 
state for their pigment date back to periods of remote 
antiquity, though for writing purposes they have to a large 
extent been superseded, at least in Europe, by inks in 
which the pigment is more or less in solution. 

The inks which may be conveniently considered under 
this heading comprise (i) Sepia, (2) Indian or Chinese 
ink, and (3) inks of the type of the ancient writing inks, 
which contain elementary carbon suspended in a suitable 
medium. 

(i) SEPIA. 

Source. The black or dark brown pigment known as 
sepia is contained in a secretion formed in a special 
glandular organ of different species of Cephalopoda, in- 
cluding the common cuttle-fish or squid. The " ink-sac " 
or "ink-bag," as this glandular organ is popularly called. 



16 INKS AND THEIR MANUFACTURE 

has strong fibrous walls, and is generally, though not in- 
variably, provided with a separate ejaculatory duct. 

Mr. Martin Duncan, who has made a study of living 
members of the Cephalopoda, which he kept in a large 
tank made for the purpose, stated in a lecture before the 




Fig. 4. Common cuttle-fish (Sepia offielna Us). 

London Camera Club, October 15, 1903, that it was not 
an easy matter to cause a cuttle-fish to exhaust its stock of 
ink. And the facility with which it would discharge the 
liquid upon the least provocation was one of the great 
difficulties with which he had to deal in prosecuting his 
inquiries ; for a whole tank full of water would be clouded 



CAKBON AND CABBONACEOUS INKS 17 

in a few seconds, and work had to be' suspended until the 
vessel had been thoroughly cleaned and refilled. He also 
stated that an exhausted cuttle had the power of renewing 
the inky secretion in as short a period 
as a quarter of an hour. 

Fig. 4 represents the common cuttle- 
fish (Sepia officinalis) from which the 
ink is obtained. By the kindness of 
the Curator of the Geological Museum, 
London, we have been able to photo- 
graph specimens of fossil Cephalopoda 
from the Blue Lias in which the ink- 
bags remain intact. It is a well- 
known circumstance that this fossil 
sepia has been more than once ground 
up with water and found to furnish an 
excellent ink. This is alluded to in 
the Bridgewater Treatise by Dean 
Buckland. In Figs. 4 and 5 the ink 
sacs are indicated by the white 
pointers. 

Mr. Henry Lcc, for some time 
Naturalist to the Brighton Aquarium, 
writing of this black fluid, says : * 

" The cuttle (sepia) discharges it on 
the slightest provocation ; and this is 
sometimes very troublesome and an- 
noying when this species is exhibited 
in an aquarium. The quantity of 
water its ink will obscure is really 
surprising. The fluid is secreted with 
amazing rapidity, and the black injec- 
tion frequently occurs several times in succession. I 
have often seen a cuttle completely spoil in a few 
seconds all the water in a tank containing a thousand 
gallons." 

The extreme diffusibility of the pigment is also referred 
to by UreJ who states that one part of sepia immediately 
renders 1000 parts of water opaque. The cuttle-fish is 



Fig. 5. Fossil sepia. 



Notes The Octopus. 



f Diet, of Cliem. Sepia. 
B 



18 INKS AND THEIR MANUFACTURE 

thus provided with a most effective weapon of defence, 
which enables it to effectually cover its retreat when 
attacked by its enemies. 

The pigment most highly valued is that obtained from 
the Mediterranean cuttle-fish, Sepia officinalis, and from 
S. loligo, and S. tunicata, though it is also prepared from 
the ink-sacs of other species. The ink-sacs are removed 
as soon as possible after the capture of the fish, and rapidly 
dried to prevent putrefaction. It is a common practice 
for the fishermen on the South Coast of England to remove 




Fig. 6. Fossil sepia. 

the ink-bags of the cuttle-fish, whose flesh they use for 
their bait, and to keep them in a dried condition until 
they can dispose of them to the manufacturers. A large 
amount of sepia is also obtained from Ceylon, where the 
cuttle-fish are collected by natives for a very low daily 
wage. 

Manufacture. There is good reason for believing that 
ink manufactured from the pigment of the cuttle-fish was 
used as a writing ink by the Romans,* but it is now pro- 
bably used exclusively in the manufacture of the " sepia " 
of the artists. 

For this purpose the dried ink-sacs are pulverised, and 
the powder triturated with caustic lye and boiled for thirty 

* Persius, loc. cit. 



CARBON AND CARBONACEOUS INKS 19 

minutes. The liquid is then filtered and neutralised with 
hydrochloric acid, and the precipitated pigment' repeatedly 
washed with water, and dried at a low temperature. 

Modifications of this process are used by different 
manufacturers, the exact details of which are regarded as 
trade secrets. 

The pigment separated from the other constituents by 
some such process as described above is ground down to 
an impalpable powder on a marble slab, usually by manual 
labour. It is then made up into cakes, or is prepared in 
a moist condition and put up in pans or tubes, or is incor- 
porated with oil for use as an oil paint. 

In purchasing the raw material the manufacturer's chief 
consideration is to see that the ink-sacs are full, not 
withered. There does not appear to be much variation in 
the colouring power of different samples of the crude 
sepia. 

Chemical Composition. It has frequently been 
stated,* though without justification, that the pigment of 
the cuttle-fish consists of finely divided carbon associated 
with proteid substances and calcium phosphate, but it is 
now known to be a complex organic compound. 

Kemp A who examined the liquid from the ink-sac whilst 
in a fresh state, found that it yielded precipitates with 
alcohol, mineral acids, tannin, and mercuric chloride. Ifc 
was very viscous, and possessed a peculiar fishy cdour, 
but little taste. He came to the conclusion that it con- 
sisted mainly of albumin, with possibly -some gelatin. 

Shortly afterwards Front J made a chemical examination 
of the black residue contained in the dried ink-sac. It 
was a hard, brittle, brownish-black substance with an 
iridescent lustre. When powdered, it yielded a violet- 
black powder without odour, but with a slightly salt taste. 
Its specific gravity was 1.640. When digested with water 
for a long time it yielded a brown solution, giving a brown 
precipitate with lead nitrate. It was found to contain 
the following constituents : Black pigment {melanin), 
78 per cent. ; calcium carbonate, 10.4 percent. ; sulphates 

* E.g., in Tomlinson's Cj/clop&dia of Useful 4 /'fa, 1854, p. 598. 
f Nicholson's Journ. of Xat. Phllos., 1813, xxxiv. 34. 
j Annals of Philosophy, 1815, v. 417. 



20 INKS AND THEIR MANUFACTURE 

and chlorides of the alkali metals, 2.16 per cent.; and 
mucine, 0.84 per cent. 

The melanin was isolated by boiling the black mass 
with successive portions of water, hydrochloric acid, and 
dilute ammonium carbonate solution. The residue thus 
obtained was a black shining powder resembling charcoal 
in appearance, and emitting a fishy odour when burned. 
It was insoluble in water, alcohol, or ether, though it re- 
mained for a long time in suspension in water. By adding 
acids or ammonium chloride to the water its separation 
was accelerated. It was partially soluble in hot potassium 
hydroxide solution, yielding a brown liquid, from which 
slight precipitates were obtained with hydrochloric or 
sulphuric acids, but not with nitric acid. The original 
pigment was quite insoluble in the two former acids, but 
dissolved in nitric acid. It was also soluble in ammonium 
hydroxide, but not in solutions of ammonium carbonate. 

A more recent research is that of Grirod* who made a 
full analysis of the liquid secreted by the ink-sac of 8. 
officinalis. He foiind it to be odourless, but having a 
slightly salt taste. 'When examined under the microscope 
the liquid was seen to consist of minute corpuscles sus- 
pended in a clear serum. 

Chemical analysis showed the liquid to consist of 60 per 
cent, of water ; 8.6 percent, of mineral matter ; 30.54 per 
cent, of insoluble organic matter ; and 0.86 per cent, of 
soluble extractives. 

The mineral matter included calcium, magnesium, 
sodium, potassium, iron, carbonates, sulphates and chlo- 
rides, though curiously it was free from phosphates. 

The pigmentary substance was obtained in a pure state 
by digesting the dried residue for four days with alcohol, 
and then for four days with ether, to remove the extrac- 
tives. It was then collected on a filter, washed, and 
digested with glacial acetic acid to eliminate albuminous 
substances, then with potassium carbonate to remove 
mucine, and finally with dilute hydrochloric acid (i : 10) 
to free it from the mineral salts. 

As thus prepared the pigment (after drying at 100 C.) 
was a black homogeneous substance, leaving no residue of 
* Ciimptes Reridus, 1881, xciii. 96. 



CAKBON AND CARBONACEOUS INKS 



21 



ash on ignition. It was insoluble in water, alcohol, ether, 
and acids, with the exception of nitric acid. It was 
bleached by chlorine and by bleaching powder, and when 
heated with soda lime evolved ammonia. 

Its elementary composition was as follows : Carbon, 
53.6; nitrogen, 8.8; hydrogen, 4.04; and oxygen, 33.56 
per cent. 




Fig. 7. Dried sepia sacs. 

Scpiaic Acid. In 1888 Ncnckl and Frau Sicler* 
obtained an amorphous substance, to which they gave this 
name, by treating the pigment melanin with fifteen times 
its weight of a 10 per cent, solution of potassium hydroxide? 
It had the following elementary composition : Carbon, 56.3 ; 
hydrogen, 3.6; nitrogen, 12.3; sulphur 0.5 ; and oxygen, 
27.3 per cent. It was found to be soluble in solutions of 
alkalies, and was precipitated from its solution by copper 
sulphate and by ammoniacal zinc chloride. 

" (7/<>iii. CentralM., 1888, xix. 587. 



22 INKS AND THEIR MANUFACTURE 

British Sepia. Through the kindness of Messrs. New- 
man we have been enabled to examine several ink-sacs of 
cuttle-fish from Southampton, in the dried condition as 
received by them. The appearance of these is shown in 
the accompanying figure (Fig. 7). The general physical 
characteristics were very similar to those recorded by 
Prout (supra), but our specimens had the distinct fishy 
odour observed by Kemp in the case of the fresh liquid, 
and this became very marked on boiling the powdered 
substance with water. 

The powder contained 17.56 per cent, of moisture, and 
on ignition over a low Argand flame yielded 12.22 per 
cent, of ash, containing the following constituents : 
Silica, 0.28 ; calcium, 1.92 ; magnesium, 1.75 ; chlorine 
(including other halogens), 1.07; sulphuric acid, 1.84; 
total nitrogen, 8.42 per cent. 

When treated with boiling water the powder dissolved 
to a considerable extent, but repeated and tedious extrac- 
tion was necessary to remove the whole of the soluble 
matter. The black residue left on the filter amounted to 
71.1 per cent, of the original substance, and contained 
7.46 per cent, of nitrogen, calculated on the original 
powder. 

The brown solution when evaporated left a brown resin- 
like deposit, which on ignition gave 4.55 per cent, of ash, 
calculated on the original substance. 

On treating the insoluble residue with boiling 10 per 
cent, potassium hydroxide, 19.23 per cent, (calculated on 
the original substance) remained undissolved. 

Examination of commercial Sepia. Most, if not all, 
of the English manufacturers prepare sepia, exclusively 
from the cuttle-fish, but there is reason to believe that a 
large proportion of the so-called " sepia " of foreign origin 
is sepia in name only. 

A chemical means of distinguishing between genuine 
sepia and preparations consisting of lamp-black or other 
forms of carbon incorporated with glue, consists of treat- 
ing the powdered sample with boiling water untij tho- 
roughly disintegrated, filtering the liquid, and thoroughly 
washing the residue. 

In \}\Q case of sepia, this residue will contain a large 






CARBON AND CARBONACEOUS INKS 23 

amount of nitrogen, and on ignition will leave a consider- 
able proportion of ash containing the constituents men- 
tioned in the previous section (p. 22). 

Lamp-black preparations, on the other hand, will leave a 
residue of practically pure carbon, containing only traces 
of nitrogen, and leaving but little ash on ignition. The 
whole of the glue, which would cause the finished prepara- 
tion to show a large proportion of nitrogen, will have been 
removed by the treatment with hot water and filtration. 

The main points to be considered in a manufactured 
sepia are the colouring power and permanency of the 
colour. 

Sepia was one of the pigments tried in the experiments 
of Dr. Russell and Sir William Abney (chap, vi.), and to 
quote the words of the latter : * " We are apt to look on 
sepia as one of the most permanent pigments ; as a matter 
of fact it is fugitive, and those who have examined sepia 
drawings made in the early part of the century will see there 
has been certainly a distinct fading in those drawing?." 

2. INDIAN OR CHINESE INK. 

The extreme antiquity of the ink manufactured by the 
Chinese has already been mentioned in the Historical Intro- 
duction. According to ancient Chinese documents cited 
by Jametel,^ the earliest ink was a kind of vegetable 
varnish, and it was not till about the third century B.C. 
that the solid product prepared from lamp-black and glue 
was introduced. The province of Kiang-si enjoyed a 
monopoly of the manufacture, and the ink attained a high 
degree of perfection, its quality being maintained by 
special ink inspectors. 

This ink has also been prepared in Japan for many hun- 
dred years. The province of Om i produced a fine quality 
known as takesa, but the taikeiluku of Yainashiro was con- 
sidered the best. At the present day the best quality of 
Japarese ink is said to be manufactured in Nara or 
Matsuda. 

* Journ. Soc. Arts, 1889, xxxvii. 113. 

f L 1 Encre de Chine, d'npres des Documents Chinois, traduits par iVf. 
Jametel, Paris, 1 882. 



24 INKS AND THEIR MANUFACTURE 

Lamp-black: Composition. Wben carbonaceous pro- 
ducts, such as oil, rosin, or tar, are burned with an insuffi- 
cient supply of air, the oxygen combines with the hydrogen 
forming water, whilst the carbon is to a large extent 
deposited in the amorphous form known as lamp-black. 




Fig. 8. Chinese manufacture of lamp-black. 

The amount of pure carbon in this soot is about 80 per 
cent., the remainder consisting of oily and resinous sub- 
stances with inorganic salts, notably ammonium sulphate. 
For ordinary commercial uses these impurities are not 
altogether disadvantageous ; but if a purer substance is 
required, the lamp-black is heated to redness in a closed 



CARBON AND CARBONACEOUS INKS 



25 



crucible to carbonise the organic substances, and then 
digested with hydrochloric acid and thoroughly washed 
with water to remove inorganic salts, the final product 
being nearly pure carbon. The purest form of lamp-black 
is obtained by passing a slow current of turpentine vapour 




Fig. 9. Chinese manufacture of ink. 

through tub3S heated to redness, and igaitiug the deposit 
in chlorine to remove the last traces of hyJrogan. 

Manufacture of Lx>ny-Ua?k: Chinee M^hrl. Th3 
old3sb msthoi of which we hive any ra^ord is that which 
has b3en usel by the Chinese for csnturies.* Various 

* Jametel, loe. cit. p. n. 



26 INKS AND THEIR MANUFACTURE 

substances have been used as the original source of their 
lamp-black, such as rice straw, pine wood, and haricot 
beans, but these have been for the most part discarded in 
favour of vegetable oils, and in particular that obtained 
from the seeds of Aleurites cordata, or tung-cil, which yields 
a brilliant black ink, deepening in tone with age. 

The oil is burned in small terra-cotta lamps, which are 
placed in terra-cotta chambers with a hole to admit air, and 
having a depression on the top in which water is placed. 
The smoke is collected in inverted terra-cotta cones with 
polished interiors, which are fixed above the flame. From 
time to time the cones are replaced by fresh ones, and the 
deposited soot removed by means of a feather, care being 
taken tc reject all oily particles. 

Figs. 8 and 9 are reproductions of two of the quaint 
illustrations copied by Jametel from ancient Chinese 
manuscripts. 

In some factories the terra-cotta condensing chamber is 
replaced by a hollow wooden ttmnel, having a hole bored 
in the wall to act as the ventilating shaft. A range of 
bricks inside supports the cones, of which about twenty 
are used at a time. 

The best season for the manufacture of lamp-black is at 
the end of autumn or beginning of winter. The terra- 
cotta condensers are placed in a room carefully protected 
from draughts, which would interfere with the regular 
deposition of the soot. The cones are examined hour by 
hour, since delay in changing them causes the lamp-black 
to assume a yellow tint. 

Julien* states on the authority of Chinese documents 
that the finest quality of ink is prepared from the lamp- 
black obtained from sesame oil, or from tung oil, whilst 
the soot of pine wood or deal is used for the commoner 
kinds. 

Strips of pine wood about 18 inches in length are burnt 
in a bamboj cabin, 100 feet in length, which is covered 
inside and out with paper, and divided into several com- 
partments by partitions, in each of which is an opening 
for the passage of the smoke. The deposit in the furthest 
compartment is the lightest and makes the best ink, whilst 
* Ann. cle Chun.. 1833, ^"- 38- 



CAEBON AND CARBONACEOUS INKS 27 

that in the first and second compartments is very coarse r 
and is sold to printers, varnishers, and house painters. 

The quality of the lamp-black has a very great influence 
upon the character of the ink, and the Imperial ink is 
prepared from the very lightest and purest that can be 
obtained. 

Old European Methods. Lamp-black is manufactured on 




Fig. 10. European lamp-black chamber. 

a large scale from the resinous- imparities obtained as by- 
products in the manufacture of turpentine, and is also 
prepared from oil, tat, &c. The initial substance is burned 
in a furnace with an insufficient supply of a^r suitably 
regulated by apertures which can be opened or closed. The 
dense smoke is conducted through a flue into a cylindrical 
stone, brick, or cast-iron chamber, the sides of yhich are 
covered with sacking or sheep-skin. An iron cone is 



28 INKS AND THEIR MANUFACTURE 

suspended within the chamber, which it fits so exactly that 
when lowered its edges scrape the suspended sacking and 
remove the deposited lamp-black (see Fig. 10). 

A small hole in the top of the cone allows the smoke to 
escape into the chimney of the cylinder, leaving most of 
its carbon behind. From time to time the suspended 
sacking is removed, scraped, and replaced. 

A more economical method is to conduct the products 
of combustion first through an iron tube, where oily 
substances are deposited, and then through a series of 
iron condensing chambers, where the carbon is deposited, 
the purest product being obtained from the final con- 
denser. This method of condensing is employed in the 
manufacture of the finest grades of lamp-black, the source 
of the smoke being fatty oils burned in lamps. 

An impure form of black of bad colour is prepared 
from certain kinds of coal, and is chiefly used for pitching 
ships. 

Other varieties of black are Spanish black from cork ; 
vine Hack from the twigs of the vine ; peach black from, 
peach kernels ; and German black, said to be obtained 
from a mixture of wine-lees, peach kernels, and bone 
shavings.* 

More modern methods of preparing black for printing 
inks are described in chap. x. 

Manufacture of Indian Ink. The fullest source of 
information on the Chinese methods 'of preparing the ink 
from the lamp-black is still C/ien-ki-Soiten's book as trans- 
lated into French by Jametcl. .From that we learn that 
the lamp-black is first sieved into glazed vases, and then 
dried in paper bags suspended in a dry chamber. The 
glue is prepared either from fish or from ox-hide, and is 
used in the proportion of four to five catties f to each 
pound of lamp-black. If too little glue be used, the ink 
is blacker, but not so permanent. The solution of the 
glue is poured through a sieve on to the lamp-black, and 
the paste thoroughly mixed and heated for fifteen minutes 
in a tightly closed vessel over boiling water. It is next 
pounded for four hours in a mortar (see Fig. 9), until the 

* Lewis, PkUotophico-technicum,) 1763, p. 377. 
f A catty = 800 grammes. 



CARBON AND CARBONACEOUS INKS 2$ 

mass becomes thoroughly pliable, after which it is mixed 
with musk and camphor and beaten into long sticks. 
These are then moulded into cakes weighing about 114 
to 140 grammes, and the cakes dried by desiccation in 
well-burnt ash from rice straw, which is replaced daily by 
fresh ash. The desiccation takes from one to three or 
four days or longer, but if the process be continued too 
long the ink becomes pale and loses its brilliancy. 

The following proportions are given as the best for an 
ink that will become blacker with age : * Lamp-black 
from dryandra oil, 10 catties ; old ox-hide glue, 4J catties ; 
old fish glue, i catty ; extract of sou-mou and another 
Chinese aromatic plant, I catty. 

The addition of a small quantity of dried ox-tongue is 
said to give a violet tint to the ink, whilst finely powdered 
vegetable matter is added to produce a bluish tint. 

The glue must be white and transparent. It was 
formerly obtained from various substances, such as rhino- 
ceros' and stag's horn, but is now exclusively prepared 
from ox-hide or from fish. A decoction of the plant 
Hibiscus mutdbilis was formerly used, but according to 
Jametel has long been discarded. 

At the present day the only essential difference in the 
ink produced by different Chinese manufacturers is that 
different proportions and methods of incorporating the 
chief ingredients are employed. 

The methods of preparing Chinese ink, which are given 
in a history of China published by du Halde, a Jesuit mis- 
sionary ,f in 1735, agree in all essential details with the 
above account. Lamp-black from pine wood or from oil 
was mixed with glue or with gum tragacanth and aromatic 
essences, and the paste pounded, and stamped into tablets, 
which were finally dried for three to ten days in cold ashes. 

In Japan the lamp-black is obtained chiefly from 
sesame oil or from pine wood, and is mixed with ox-hide 
glue in a copper vessel surrounded by another vessel con- 
taining hot water. The plastic mass is beaten in wooden 
moulds into cakes, which, as in the Chinese method, are 
dried by contact with absorbent ash. 

* Jametel, loc. clt. p. 28. 

f Description cle V Empire He la Chine, Parin, 1735, ii. p. 245- 



30 INKS AND THEIR MANUFACTURE 

Eislcr * describes a method of preparing Indian ink 
from animal and vegetable charcoal mixed with milk and 
thick gum water, and allowed to dry into cakes. 

A modern (European) method of preparing Indian ink 
consists of triturating the lamp-black with a dilute 
solution of potassium hydroxide, so as to form a cream. 
This is poured in a thin stream into slightly alkaline 
water, and the deposit collected, washed with water, 
dried, and incorporated with a decoction of the seaweed 
known as Irish moss or carrageen, to which a little musk 
has been added. 

In another process, a solution of gelatin is boiled under 
pressure for two hours, and then for one hour more, over 
an open fire until suitably concentrated, and then mixed 
with lamp-black that has been heated to redness in a 
closed crucible. The object of heating the gelatin is to 
convert it into the so-called gelatin-peptone, which does 
not solidify like ordinary gelatin. Indian ink thus pre- 
pared does not gelatinise in cold weather. 

Merim4e f a ^ so prepared Indian ink by mixing a strong 
decoction of galls with a solution of glue, washing the 
precipitate with water, and dissolving it in a fresh solution 
of glue, which is then concentrated to the required con- 
sistency and mixed with lamp-black. Dextrin js some- 
times used in place of gelatin or glue in the manufacture 
of cheaper qualities. 

.Lenher% asserts that he has prepared Indian ink of 
equal quality to the best kinds obtained from China by 
the following method : Petroleum or turpentine oil is 
burned in lamps to which the supply of air is limited. 
The smoke is conducted through a zinc tube, 100 feet 
in length, the inclination of which is slightly upwards. 
The soot deposited at the remote end of the tube is in a 
very fine state of subdivision, and requires but little 
purification to free it from the tarry matter which, if not 
removed, would cause the ink to have a brownish tint. 
For this purpose it is first boiled with nitric acid, then 
washed with water by decantation, then boiled with strong 
sodium hydroxide solution, and finally washed and dried. 

* Dintefass, 1770, p. 31. f loc. cit. p. 197. 

I Die Tinten Fabrikation, 1880, p. 180. 



CARBON AND CARBONACEOUS INKS 31 

The purified product, consisting of nearly pure carbon, 
is mixed into a paste with a clear solution of guin, and 
heated and stirred until evaporated to the required con- 
sistency. It is now allowed to cool gradually, a little 
tincture of musk being added before it quite sets, and is 
finally kneaded on a flat plate, and pressed into metal 
moulds, from which the rods are ejected by tapping. 

An inferior kind of ink has been prepared by Lcnher 
from ordinary soot purified in a similar manner. This 
method of preparing ink from purified soot was published 
long before Lcnlicrs book appeared.* 

In this country little, if any, Indian ink now appears to 
be manufactured in the form of cakes. During the war 
between China and Japan there was a great dearth of the 
ink, and although some of the largest dealers tried every 
possible source to obtain a supply, they were unable to do 
so. From this it would seem that the solid product is now 
only to be procured from the far East. 

This conclusion receives further confirmation from the 
fact that a large firm dealing in artists' materials now 
supplies much more of a liquid preparation of lamp-black 
than of the cakes of Indian ink. 

Qualities of Indian Ink. The ink is imported into 
England from China in the original boxes, each holding 
i Ib. According to the size of the sticks, 8, 20, or 40 
may go to the pound, and are spoken of in the trade 
as "eights," "forties," &c. The sticks are of various 
forms, some being in squares, some in tablets, and some 
octagonal/ The best qualities of sticks are generally dis- 
tinguished by being gilt, and are stamped with very fine 
impressions, such as dragons, lions' heads, &c., which 
denote different qualities well recognised in the trade. 
They are obtained from Yutshing and Yenshing. 

The octagonal sticks are also of very fine quality. The 
sticks known as " Mandarin " are of fine quality, and are 
distingushed from ordinary sticks, which have also a lion 
on the top, by having a finer impression of the Chinese 
characters on their sides. The commonest kind are in the 
form of small sticks with white letters on the side. 

* Dingier* g polyt. Juurn. 1832, xliv. 237. 



32 INKS AND THEIR MANUFACTURE 

Examination of Indian Ink. Among the Chinese the 
quality of ink is tested by rubbing the tablet on the 
palette. If only a faint sound is heard the ink is con- 
sidered to be of good quality (Si-mo), but if a loud noise is 
produced it is regarded as inferior (Tsou-mo). 

When rubbed with water, Indian ink should yield a 
uniform liquid, free from coarse particles or flakes. The 
best Chinese inks have a brilliant violet shade, whilst inks 
of the second quality are brilliant black, and inferior inks 
have a yellow tint. A good ink should not lose its inten- 
sity or brilliancy on keeping, and should colour paper a 
brilliant black. Inferior inks lack either blackness or 
brilliancy, or both. 

A practical test of the quality of an ink made from pine 
soot was recommended by Julien* This consisted in 
leaving a fragment in water, and noting the time before it 
rose to the surface. The better the quality the longer the 
ink was said to remain submerged. 

Practical Tests. We submitted several of the different 
grades of Chinese ink to practical tests, first of all re- 
ducing each to powder, and immersing o. I grm. in 10 c.c. 
of water. It soon became apparent that the better-class 
inks were far more readily soluble in cold water than were 
the cheaper kinds, some of the latter hardly colouring 
the fluid after some hours' soaking. The various samples 
were then put in a water-bath and raised to the boiling- 
point, but the cheaper grades were still more refractory 
than the others, and required to be rubbed down in a 
mortar before the particles of carbon were diffused in the 
liquid. After allowing the containing bottles to rest for 
an hour, it was found that the sediment of the best samples 
of ink was of a much finer character than that of the 
others. 

Our next experiment was to test the tinctorial value of 
the different samples by applying the solutions to What- 
man paper, first of all with a full brush covering a long 
strip of paper while it was pinned on a sloping drawing- 
board. Each strip of paper was treated with a different 
sample of ink, and when the first coat was dry, a second 

* Ann. de Chim., 1833, liii. 314. 



CARBON AND CARBONACEOUS INKS 33 

was applied, not covering the whole of the strip, but 
leaving a small portion at the end with the first coating 
untouched. A third, fourth, and fifth coat followed, each 
falling short of the preceding one, until at the end of the 
strip a strong black represented the sum of all. A glance 
at the results at once showed the advantage of employing 
the better class of ink, for the cheaper kinds were by 
comparison lacking in covering power, and there were 
present particles of carbon which gave rise to streaks 
under the brush. The best inks worked far more smoothly 
than the inferior kinds, and opacity was reached with 
fewer washes. And from what has been already stated it 
will be evident that in the better class of material the 
labour of rubbing down the pigment from the solid stick 
is reduced to a minimum. From our examination of the 
sediment formed in the inks under examination, it would 
seem that in the better grades lamp-black of much finer 
quality is employed than is used in the manufacture of the 
cheaper kinds. 

These sticks of Chinese ink are exceedingly brittle, and 
those rendered unsaleable by breakage are commonly 
ground up in water to form the liquid ink so much 
employed by draughtsmen and artists in " black and 
white.'" 

Chemical Composition of Commercial Indian Inks. 
The specimens of the four grades of ink submitted to 
the practical tests described above gave the following 
results on analysis : 



Indian Ink. 


Water. 


Carbon 
residue. 


Nitrogen 
in 
residue. 


Nitrogen 
in 
Original 


Ash. 










Ink. 






Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


I. Octagonal stick . 


8.16 


53-9 


0.0 


7-74 


4.08 


II. Lion stick, tine 












letters 
III. Lion stick, coarse 


7.20 


52-53 





4.87 


3.69 


letters 
IV. Small stick, coarse 


9-93 


49.64 





7.26 


4-96 


letters 


9.40 


57-04 





6.84 


4.OI 



34 INKS AND THEIR MANUFACTURE 

The fact that the residue left, on extracting the soluble 
substances with hot water, is free from nitrogen, affords 
simple means of distinguishing between Indian ink and 
pure sepia (see p. 22). 

3. CARBON WRITING INKS. 

Ancient Carbon Inks. The characters on Egyptian 
papyri and in Latin and Greek MSS. are frequently much 
darker and more distinct than those written centuries after 
with modern iron-gall ink. The latter can be readily 
destroyed by various chemical agents, such as acids and 
bleaching agents, and their permanency is also largely 
dependent on the relative proportion of iron and tannin in 
the ink, and on the manner in which they have been kept. 

Astle, who was Keeper of Records in the Tower of 
London, and thus had exceptional opportunities of study- 
ing MSS. of all ages, found that the black ink used by the 
Anglo-Saxons in documents of the seventh, eighth, ninth, 
and tenth centuries had preserved its original intensity 
much better than that used at later periods, especially in 
the sixteenth and seventeenth centuries, which was fre- 
quently very faint. It was rare to find faded writing in 
documents before the tenth century. Astlc * came to the 
conclusion that this was due to the earlier inks containing 
carbon ; but Blagden, on testing the writing with potas- 
sium ferrocyanide, found that iron was present in every 
instance.f 

It is impossible to determine the exact period when 
carbon inks were replaced by iron-gall inks, though it was 
probably early in the present era (cf. Historical Introduc- 
tion). 

The ink of the Greeks and Latins, like the modern 
Oriental inks, was a mixture of finely divided carbon with 
a solution of gum or glue, sufficiently dilute to flow from 
a reed. In reality they were only modifications of the 
Chinese inks described above, and in some cases were even 
dried before use. Thus Vitruvius + states that atramen- 

* Origin of Writing, 1803, p. 209. 

f Trans. Roy. Soc,, 1787, Ixxvii. [ii.] 451. 

j Lib. vii. 10. 



CAEBON AND CARBONACEOUS INKS 35 

turn was prepared from the soot of pitch pine collected on 
the walls of a marble chamber, mixed with gum (glutinum) 
and dried ; and Dioscorides * gives the proportions of soot 
to gum as three to one. 

Evidently the brilliancy of the black deposit and the 
more fluid character of iron-gall inks led to their gradually 
superseding carbon inks for writing purposes, of which no 
mention is made in mediaeval literature. 

It is true that Wecker in 1582 gave a formula for an 
atramentum 'perpetuum, but this was really a printing ink 
consisting of linseed oil and lamp-black, and there is no 
reference to an aqueous carbonaceous ink in his book or in 
that of Oanneparius ( 1 660). 

Modern Carbonaceous Inks. Lewis ^ in 1764 made 
various suggestions for rendering ink more permanent, 
some of which are described more fully in chap. xiv. 
His principal plan was to add finely divided lamp-black or 
ivory black to a good iron-gall ink, but such ink could be 
bleached by chemical means to destroy the gall ink and 
then washed with water to remove the carbon. 

Other chemists have made use of an essential oil, or of a 
varnish or saponified resinous substance, or a solution of 
gluten, to retain the carbon in suspension. Of various old 
formulae on these lines mention may be made of the 
following : 

Westrunitfs Ink.\ Galls, 3 parts ; Brazil wood, I part ; 
water, 46 parts. Boil until reduced to 32 parts. Strain 
and add ferrous sulphate, ij part ; gum arabic, ij part; 
indigo, i-J part; and lamp-black, f part. 

Close's Ink. Powdered copal (25 parts), in lavender 
oil (200 parts), mixed with lamp-black (2\ parts), and 
indigo (I part). If too thick the ink was thinned with 
turpentine. 

Sheldrake's Ink.\\ A mixture of asphalt dissolved in 
turpentine with amber varnish and lamp-black. The whole 
question of the best means of rendering writing safe from 
attempts to remove it is discussed in chap. xiv. 

* Opera, lib. v. cap. 183. t loc. cit. 

Nicholson's Journ. of Nat. Philosophy 1802, iv. 479. 
Nicholson's Diet, of Chem., 1820. || Ibid. 



CHAPTER II. 

TANNIN MATERIALS FOE INKS. 

CONTENTS. Galls : Origin Aleppo galls Chemical composi- 
tionChinese galls Chemical composition Japanese galls 
Acorn galls Oak-apple gaily Other galls Tannins Classi- 
fication of tannins Suitability of tannins for ink-making 
Chestnut bark and wood Chestnut extract Chestnut 
tannin Ink from chestnut wood Sumach Sumach tannin 
Ink from sumach Divi-divi Divi-divi tannin Ink from 
divi-divi Myrobalans The tannin of myrobalans 
"Valonia The tannin of valonia Ink from valonia Oak- 
bark tannins Reactions of oak tannins Amount of tannins 
in oak bark Ink from oak bark Q-allotannic acid Fer- 
mentation of gallotannic acid Properties Gallic acid 
Properties^-Reactions distinguishing between gallotannic and 
gallic acids. 

GALLS. 

Origin. Curious vegetable excrescences, known as galls, 
are frequently formed upon the branches, shoots, &nd 
leaves of trees, and especially upon the oak. They are 
produced by the female of certain species of insects, of 
which the best known are the hymenopterous gall-wasps 
(Cynipidce), which puncture the young tissues and deposit 
their eggs. Under this stimulus the plant juices accumu- 
late at the point of puncture, and a gall is gradually 
formed, which serves as the home of the larva. It is pos- 
sible that some virus injected simultaneously with the egg 
plays a part in the development of the gall, but the main 
essential appears to be the presence of the living larva. 
Should the egg of the insect perish from any cause no gall 
is formed, or if the larva dies the gall ceases to grow. 

Galls vary greatly both in size and shape, some, e.g., the 
Californian " flea seed," being very minute, whilst others, 
like the large galls on the roots of certain oaks, are several 
inches in diameter. Some galls are round and smooth like 






TANNIN MATERIALS FOR INKS 



37 



the English oak-apples ; others, like the Aleppo galls, are 
crowned with protuberances ; whilst others again assume 
fantastic forms, as in the case of the " artichoke gall " 
found on certain French oaks, the curious English galls 

shown in Figs. II, 12, and 
13, and the Chinese and 
Japanese galls (Figs. 17 and 
1 8). The forms and colours 
of the different kinds of 
galls are remarkably con- 
stant, and afford a means of 
distinguishing between the 




Fig. ii. English double 
oak-apple gall. 





Fig. 12. English oak gall. 



Fig. 13. English gall. 



insects, often of very similar appearance, that produce 
them. 

In the majority of cases galls contain only one larva, 
and are described as " monothalarnous," whilst others 



38 INKS AND THEIR MANUFACTURE 

afford shelter and food to a colony of larvae, and the term 
" polythalarnous " is applied to them. 

Aleppo Galls. The ordinary nut-galls of commerce are 
commonly known as Aleppo, Turkey, or Levant galls. 
They are produced by the female of a gall wasp, Cynirjs 
gallon tinctorice, upon the branches of a small oak, Quercus 
infectoria, which is abundant on the Syrian coast, and on 
the east of the River Jordan. The insect pierces its way 
out of the gall after five to six months, and the unin- 
habited galls are then known as white galls, from their 
pale colour. These contain considerably less tannin than 
galls which still enclose the larva, and have therefore a 






Fig. 14. Green Fig. 15. White Fig. 16. Section 

Aleppo gall. Aleppo gall. of white gall. 

smaller commercial value. The best galls are selected 
ahead and harvested before the insect escapes, and from 
their colour are known as blue or green galls. 

The value of a given sample of galls depends to a large 
extent upon the proportion of white galls it contains. 
Hence, fraudulent attempts are sometimes made to arti- 
ficially close the holes left by the insect, and so make the 
galls to appear to still contain the larva.* A section of 
the nut would readily detect this fraud (see Fig. 16). 
Aleppo galls vary somewhat in size, but usually average 
from 8 to 15 mm. in diameter. They are globular or 
pear-shaped, and are crowned with numerous tubercles 
(Fig. 13). The colour ranges from greenish black to pale 

* Allen, Commercial Organ. Anal. 



TANNIN MATERIALS FOR INKS 39 

yellowish green, whilst the interior is pale brown or 
yellowish green. 

The appearance of white galls is shown in Fig. 1 5 , and 
in section in Fig. 16, the latter showing the small 
canal through which the insect made its way to the 
surface. 

When a thin section of an inhabited gall is examined 
under the microscope it is seen to consist of an external 
layer of small cells, forming a sort of bark : beneath these 
are cellular layers of parenchyma, some of the cells con- 
taining tannin and chlorophyll ; then come radial cells 
surrounding the central cavity, in which lies the larva in 
the midst of an alimentary mass. 

Smyrna galls appear to be a commercial variety of 
Aleppo galls, being somewhat larger and darker in colour, 
and often containing a larger proportion of white galls. 

Chemical Composition. By treating 500 grains of the 
best Aleppo galls with distilled water, Davy* obtained an 
infusion of specific gravity 1.068, containing 185 grains 
of solid matter, consisting of 70.27 per cent, of tannin ; 
16.75 P er cent, of impure gallic acid ; 6.48 per cent, of 
gum and other extractives; and 6.50 per cent, of salts of 
calcium and other metals. From the results of tannin 
determinations made by later chemists there appears to 
be little doubt that Davy had not extracted the whole of 
the soluble constituents of the galls, for on this basis the 
insoluble woody fibre amounts to 63 per cent, of the total 
substance. 

In 1845 Guibourt^ made a very exhaustive examination 
of Aleppo galls ; and his results, still quoted as final in 
text-books, are as follows: Tannin, 65.00; gallic acid, 
2.00 ; ellagic and luteogallic acids, 2.00 ; chlorophyll, 
0.70; brown alcoholic extract, 2.50; gum, 2.50; starch, 
2.00 ; woody fibre, 10.50 ; sugar, proteid, potassium and 
calcium salts, 1.30; and water, 11.50 per cent. 

A later, though less complete, analysis is that of Watson 
Smith, who found Aleppo galls to have the following 
composition: Tannin, 61.65; gallic acid, 1.60; woody 

* Trans. Roy. Soc., 1803, xciii - 2 33- 

t Archiv. der Pharm., 1846, li. 190; Hist. Xat. des Drogues, 1849, ii. 
p. 286. 



40 INKS AND THEIR MANUFACTURE 

fibre, 15.68 ; water, 12.32 ; and colouring matter and 
loss, 8.75 per cent. 

Biichne-r* obtained the following amounts of extractive 
matter by treating the powdered galls with different 
solvents : 

Per cent. 
Substances extracted by ether .... 77.00 

,, by ether and alcohol . 80.40 

,, ,, by cold water . . . 86.50 

A specimen of commercial nut-galls examined by us 
contained 44 per cent, of tannin, determined as gallo- 
tannic acid by the method described in chap. iii. 

Chinese Galls. The curious variety of galls exported 
from China are not formed by a gall- wasp like most of 
the commercial galls, but are produced by a small aphis 
(Aphis Chinensis) upon the leaf, stalks, and shoots of Ehus 
semialata, a tree growing abundantly in sandy places in 
Northern India, China, and Japan. 

The aphis is about ^V of an inch in length by about 
T V in breadth at the base of the abdomen, which gradually 
widens out from the thorax (see Fig. 19, p. 45). 

The gall is at first dark green, and gradually changes 
to yellow before the larva escapes through the walls 
bursting open, the Chinese peasants collecting them 
shortly before the change takes place. The aphides are 
killed by exposing the galls in osier baskets to the action 
of steam. 

The gall is naturally covered with a light powder 
termed " salt powder" by the Chinese, and used by them 
for flavouring soup and as a medicine. f As imported 
into Europe the galls are pale grey in colour, and have a 
hornlike appearance, and a curious odour resembling that 
of freshly tanned leather (Hepwortli and Mitchell). They 
vary greatly both in size and in form, but a characteristic 
shape is shown in Fig. 17. They have a horn-like texture, 
and when broken open present a hollow interior contain- 
ing a little chalk-like dust with darker particles, which 
when examined under the microscope are seen to be dried 
aphides. 

* Rep.f. Pharm., 1851 [3], vii. 313. 
f Pereira, Pharm. Journ., 1844, iii. 384. 



TANNIN MATERIALS FOE INKS 



41 



According to von Rebling* an average-sized gall contains 
more than 3000 aphides, and by treating the debris with 
warm water these swell up to about -^ of an inch in size. 

DLL Halde\ gives a description of these galls, which, 
he states, are termed ou-poey-tse by the Chinese and are 
used by them in the preparation of various medicinal 
compounds. He also states that their formation is due 
to a small insect. 

Chinese galls were first imported into Europe in the 
eighteenth century under the 
name of " Oreilles des Indes," 
but they did not become a regu- 
lar article of commerce until 
about 1850. They are now 
largely used in Germany and 
America as the raw material for 
the manufacture of tannic acid, 
and they form one of the princi- 
pal and cheapest tannin materials 
for the manufacture of ink. In 
fact, according to Dieteridi,^ gall 
inks are now prepared from them 
almost exclusively in Germany. 

Biichner compared their com- 
mercial value with that of ordinary 
gall-nuts. In 1851 good average 
blue Aleppo galls cost iocs, to 
1058. per cwt. , whilst Chinese galls 
fetched 6$s. to 68s. per cwt. Thus, taking into account 
the amount of readily soluble tannin in the latter, they 
were I J to I J times cheaper than Aleppo galls. 

Chemical Composition. Specimens of Chinese galls were 
examined in 1817 by Brande,\\ who found them to yield 
75 per cent, of soluble matter to cold water, the residue 
consisting of woody fibre with 4 per cent, of resinous 
matter soluble in alcohol. The residue from the aqueous 

* Archiv. f. Chem., 1855, cxxxi. 280. 

t Description de V Empire, de la Chine, 1735, p. 496. 

| Pharm. Manual, 1897, p. 680. 

Rep. f. Pharm., 1851 [3], vii. 329. 

|| Trans. Roy. 8oc., 1817, evil. 39. 




Fig. 17. Chinese gall. 



42 INKS AND THEIK MANUFACTURE 

extract was found to consist mainly of tannic acid with a 
little gallic acid. 

From the absence of extractives (gums, &c.), Brande 
concluded that these galls would not be suitable for 
tanning purposes, and, in fact, he found that leather 
prepared with them was very brittle when dried. On the 
other hand, he found this property rendered them par- 
ticularly suitable for the manufacture of ink, and the ink 
prepared from them proved to be less liable to become 
mouldy than that from ordinary galls. 

In 1849, Stein* described a variety of Chinese galls 
as possessing an odour of tobacco, and containing the 
following constituents: Ash, 2. CO; tannic acid, 69.14; 
other tannins, 4.0 ; green saponifiable fat, 0.97 ; starch, 
8.20; woody fibre, 4.9; and " inert " matter, 12.96 
per cent. 

The tannin was completely extracted by boiling the 
powdered galls three times with eight times their weight 
of water. It was regarded by Stein as identical with the 
tannin of ordinary galls. 

The ash contained potassium, calcium, magnesium, 
iron, chlorine, and phosphoric acid. 

Bley's-\ results are similar to those of Stein, viz., gallo- 
tannic acid, 69.0; resin and fat, 3.0; gallic acid, ex- 
tractives and protcids, 4.0; starch, 7.35; woody fibre, 
8.65 ; and water, 8.0 per cent. 

Buclmer's^ analysis in 1851 gave the following results : 
Tannic acid, 76.97; fat and resin, 2.38; extractives 
soluble in water and some salts, 0.89 ; gums and salts, 
5.94; and starch, woody fibre and mineral matter, 13.82 
per cent., calculated upon the substance dried at 100 C. 

When extracted with ether these galls yielded 79.35 per 
cent, of soluble matter, of which 76.97 per cent, (on the 
original substance) dissolved in water. Buchner was 
unable to confirm Stein's conclusion as to the presence of 
other tannins in addition to gallotannic acid. He also 
came to the conclusion that the tannic acid was identical 
with that of oak-bark, and that gallic acid was only pre- 

* Dingler's polyt. Journ., 1849, cxiv. 433. 
t Archil-, d. Pharm., 1850, cxi. 297. 
j loc. clt, p. 323. 



TANNIN MATERIALS FOR INKS 43 

sent in the galls in very small proportion. The mineral 
matter was found to consist principally of magnesium 
phosphate. 

Tannic Acid. The proportion of tannic acid found by 
titein, Bley, and Buchner is substantially the same when 
calculated upon the dried substance, viz., Stein, 79.43 per 
cent.; Blcy, 75 per cent.; and JJnchner, 76.97. 

Viedt * gives the proportion of tannic acid in Chinese 
galls as about 72 per cent., whilst Iskikama t found 77.4 
per cent. 

Samples recently analysed by the authors J have given 
the following results: Moisture, 10.70; ash, 1.43; and 
substances soluble in water, 78 per cent. The tannin 
determined by Procter's method was 68 per cent. 

Viedt (loc. cit.) asserts that Chinese galls do not contain 
the necessary ferment for the conversion of the gallo- 
tannic acid into gallic acid, and that therefore they cannot 
be used for the manufacture of ink unless a small propor- 
tion of Aleppo galls or of yeast be added to the infusion. 

We are unable to confirm Viedt 1 s statement, which is 
also altogether at variance with the results obtained by 
van Tieghem, who has clearly demonstrated that the con- 
version of tannic acid into gallic acid is brought about not 
by a pre-existing ferment, but by the action of certain 
mould fungi, 

We have prepared ink by adding ferrous sulphate to a 
decoction of Chinese galls without any addition of either 
yeast or other galls, and found that it behaved just like 
ordinary gall ink, giving a writing which rapidly became 
black on exposure to the air. 

Moreover, insoluble deposits formed on exposing the 
ink to the iiir, and these deposits contained 6.86 to 7.56 
per cent, of iron, results very near to those obtained with 
ink from gallotannic acid or ordinary Aleppo galls. 

Japanese Galls. These galls are closely allied to the 
Chinese galls, and are frequently stated to be identical 
with them. They are produced by Aphis Chinensis, or an 

* Dingier" 1 * polyt. Journ., 1875, ccxvi. 453. 

f Chem. Xews, 1880, xlii. 274. 

j Unpublished. 

Coiiqrtes Rendits, 1867, Ixv. 1091. 



44 INKS AND THEIR MANUFACTURE 

allied aphis upon tbe shoots of Rims japonica (Siebold) or 
Rlius javanica (Murray). (See Fig. 20, p. 45.) They 
must, however, be regarded as at least a distinct variety, 
and in fact they are so recognised in commerce, though 
for ink manufacture the two varieties are used indis- 
criminately. According to Procter * the Japanese galls 
are smaller and paler, and are usually more esteemed. 

Ishikama t states that considerable quantities of Chinese 
galls were formerly imported into Japan, but that in 1880 
only the native product was used. The Japanese galls 
(Kibushi) are plucked from the trees between July and 
September, and are placed in boiling water in wooden 

tabs for thirty minutes, and 

-p, ^*f\. then dried in the sun for 

^1 three to four days. They are 

^HB }f' \ stored in warehouses in 

4BBM 11) Kiyoto, often for several 

years, before being used. 

C| The reactions given by the 

j^Jp tannin they contain are iden- 
tical with those of ordinary 
gall-nut tannic acid. 

Fig. 1 8. Japanese gall. The amount of tannin de- 

termined by the permangan- 
ate process in seven samples of different ages up to eight 
years ranged from 58.82 to 67.7 per cent. The old galls 
were very brittle, and gave much darker decoctions than 
the fresh galls, but did not contain less tannin. 

The commercial Japanese galls that we have had the 
opportunity of examining J undoubtedly differed both in 
size and shape from the Chinese product, were also softer, 
and had very much thinner walls. A typical Japanese 
gall is shown in Fig. 18. These galls contained 10.46 per 
cent, of moisture, 1.96 per cent, of mineral matter, and 
yielded 50 per cent, of tannin when boiled for three hours 
with successive portions of water. 

Mr. R. M. Prideaux, who has kindly made a micro- 
scopical examination of the debris in some of these Chinese 

* Text-book of Tanning, p. 28. 
f Ckem. News, 1880, xlii. 275. 
j Unpublished results. 



TANNIN MATERIALS FOR INKS 45 

and Japanese galls, informs us that the two aphides are 
not demonstrably of different species. Those from the 
Chinese galls were uniformly smaller than those from the 
Japanese galls, and lacked the rudimentary wings of the 
latter ; but it would be necessary to follow out the entire 
life history of both in the growing galls before being able 
to deteruiine with any certaint}^ the specific value of the 
differences observed in the dead debris. (See Figs. 19 
and 20.) 

Acorn Galls (Knopperri). These galls, also known as 
Piedmontesc galls, are produced by the female of Cynips 








Fig. 19. Aphis from Fig. 20. Aphis from 

Chinese gall, x 18. Japanese gall, x 18. 

quercus-calicis on different oaks (Q. pedunculate, Q. sessi- 
flora, &c.), in the forests of Austria and Hungary, espe- 
cially in Dalmatia, Slavonia, and Croatia. It is a large 
gall, 35 to 50 mm. in length, by 35 to 40 mm. in breadth, 
resembling Aleppo galls in having a crown of five or six 
points at the top. The interior is spongy, and has a 
spheroidal chamber containing the larva in the centre. 
This gall is the same as the pomme de Chene of Rtaumur* 
The galls are collected from August to October, after 
they have fallen from the trees, and are sold either whole 
or in the form of powder, or as an extract. They contain 
less than 45 per cent, of tannin, which, according to Lowe^ 
is the same as that of other galls, giving analytical results 
corresponding with the formula, C 14 H 10 9 . 

* Diet, des Sciences Medicales, art. '' Galles." 
f Zeit. anal, Chem., 1875, xiv - 4 6 - 



46 INKS AND THEIR MANUFACTURE 

Eitncr * made an examination of the Knoppern collected 
in 1884 in different districts of Austria, and found them 
to contain about 12 per cent, of moisture, whilst the pro- 
portion of tannin ranged from 23.94 to 35.02 per cent. 

Knoppern galls are sometimes used in the manufacture 
of ink, though according to Viedt f their use is not com- 
mon, probably owing to their comparatively low propor- 
tion of tannin. 

A similar gall is also produced on the Quercus infectoria 
of Asia Minor, but is spherical, and has the tubercles 
round the centre instead of at the top. 

Oak- Apple Galls. The common galls known in England 

as oak apples are produced by a species 

A ^^^^^ of Cynips on the branches of the oak, 

f ^fl| ^|k Quercus robur, and appear to be closely 

J M ,\ allied to, if not identical with, the gal Is 

Ijl I formed on that oak throughout Central 

Mr^ & I Europe. 

They are perfectly spherical (see 
Fig. 21), and of a light greyish-green 
J or reddish colour. 

British galls contain very much less 

Fig. 2i.-0ak-apple tannin than Ale PP g alls > and generally 

gall. less than Knoppern. Braithwaite J 

obtained only an insignificant amount 

from Devonshire galls, but did not state what method of 

determination he employed. 

In 1856 Vinen made an examination of the galls pro- 
duced by Cynips quercus pctioli, after the escape of the 
insect. 100 parts of the galls digested with ether and 
water gave 26.74 parts of extract, containing 17 parts of 
tannic and gallic acids. According to Vinen these galls 
were at that time used in Devonshire for the manufacture 
of ink. 

In 1847-48 the oaks in East Devonshire became in- 
fected with Cynips Kollari (Fig. 22), and the galls also 
appeared suddenly in 1860 in great quantities in the woods 

* Dingler's polyt. Journ., 1885, cclv. 485. 
t Ibid. 1875, ccxvi. 453. 
J Pharm. Jtntrn. Trans., 1855, xv. 544. 
Hid. 1856, xvi. 137. 



TANNIN MATERIALS FOR INKS 



47 



to the North of London. According to D' Urban* these 
galls contained a considerable amount of tannin and made 
excellent ink. 

As there was considerable doubt as to the commercial 
value of British galls, and conflicting statements had been 
published as to the amount of tannin contained, Judd 
made a series of experiments on galls at different seasons, 
the tannin being precipitated in each case by means of 




Fig. 22. Gall wasp (CynijJis Kollari}. x 5^. 

alum and gelatin. He found that old galls hanging on 
the trees in December contained on the average 15.97 P er 
cent, of tannin, whilst mature imperforated galls gathered 
in August contained on the average 17.65 per cent., and 
half-developed and shrivelled galls 13.44 per cent. 

An ink of average quality was prepared from the old 
perforated galls. 

An analysis of a specimen of Cheshire galls made by 
Watson Smith in 1869 gave the following results : Tannin, 
* Pharm. Joum. Trans., 1863, xxii. 520. 



48 INKS AND THEIK MANUFACTURE 

26.71; gallic acid, trace; woody fibre, 47.88; moisture, 
20.61 ; and colouring matter and loss, 4.80 per cent. 

Specimens of old oak-apple galls collected by us during 
the winter in Surrey contained only 1 1 per cent, of tannin 
as determined by Procters hide-powder method, but when 
examined by a colorimetric method the amount of gallic 
and tannic acids in terms of gallotannic acid was 30.7 
per cent. 

These galls yielded a good ink, and there seems to be no 
reason why English galls should not be used in admixture 
with the richer foreign varieties by ink manufacturers. 

The French galls sometimes met with in commerce are 
slightly larger than ordinary oak-apples, which they 
closely resemble in general appearance. They are formed 
upon the shoots of Quercv.s ilex in Mediterranean districts. 
Probably some of the varieties of Punjab galls are 
obtained from this species of oak. 

Other Varieties of Galls. There are numerous other 
kinds of galls, some of which are of considerable impor- 
tance as tanning materials, but they do not appear to have 
been used in the manufacture of ink, though probably 
some of them would be suitable for the purpose. 

The small-crowned Aleppo galls, which are occasionally 
found mixed with ordinary Aleppo galls, are also pro- 
duced upon Quercus infectoria, but by a different insect 
((7. polycera). They are about the size of a pea, and have 
a circlet of small projections at the top. 

Pistachio galls are produced by Anopleura lentisci on 
plants of the pistada order, and are exported from Bok- 
hara together with pistachios. They are red galls, about 
the size of a cherry, and have a characteristic taste. 

Mecca or Bassorah galls are produced upon an oak by 
Cynips insana. According to an analysis by Bley* they 
have the following composition: Tannic acid, 26.00; 
gallic, 1.60; fatty oil, O.6o ; resin, 3.40; extractives and 
salts, 2.00 ; starch, 8.40 ; woody fibre, 46.00 ; and moisture, 
12 per cent. 

Tamarix galls, also known as red galls, are formed on 
Tamarix orientalis and other plants of the same order. 

* Archil", der Pharm., 1853, Ixxv. [2], 138. 



TANNIN MATEEIALS FOR INKS 49 

They are of a bright red colour, and are about I cm. long 
by 0.5 cm. broad. They are extensively employed in dyeing 
and tanning, and in India they are used medicinally by 
the natives. Similar galls are produced on T. articulata 
in Morocco. 

The galls formed on the American " live oak," Q. virens, 
contain 40 per cent, of tannic acid, and are very similar to 
Aleppo galls. A soft, spongy, and very astringent gall is 
formed on the Californian oak, Q. lobata.* 

Terebinth galls are due to the action of aphides on 
certain species of Terebinthacecc growing in the countries 
bordering on the Mediterranean. They are red in colour, 
long and flat, and have horn-shaped projections. Within 
them is a large cavity in which fragments of the aphides 
can usually be discerned. They contain a considerable 
amount of tannin and a resinous juice that readily exudes. 
These galls are sometimes termed apples or galls of Sodom. 

Watt\ states that the galls produced upon Pistacia 
terebinthus in India are regarded by the natives as value- 
less, though the leaves are used for dyeing and tanning. 
They are sold in Bombay as pistachio galls. 

TANNINS. 

The substances to which the general name " tannin " 
has been applied are compounds possessing certain com- 
mon chemical and physical characteristics. They are 
widely distributed throughout the vegetable kingdom, and 
it is not improbable that many of them are individual 
substances, just as are the different fatty acids that occur 
in vegetable oils. 

When separated in a state of purity or approximate 
purity, tannins are odourless white or brown substances, with 
a very astringent taste. They are insoluble in chloroform 
and carbon bisulphide, but dissolve in water, alcohol, and 
ether. They yield blue or green insoluble compounds with 
iron salts, and most of them are precipitated by potassium 
chromate. They also usually combine with antimony, with 
lead, arid many other metals to form insoluble salts. With 

* Trimble, Tlie Tannins, vol. i. p. 63. 
f Diet, of Economic Products. 



50 



INKS AND THEIR MANUFACTURE 



lime water they yield precipitates of varying colour, and 
with gelatin they form an insoluble compound (leather). 

Tannins are soluble in concentrated sulphuric acid, the 
solution on heating becoming first red (rufigallic acid), and 
then black (metagallic acid). They are oxidised by nitric 
acid and l>y potassium permanganate, the latter reaction } 
forming the basis of a quantitative method of determination 

Classification of Tannins. Tannins are frequently 
described as " iron-blueing " or " iron-greening," ac- 



lull t 

tu- / 

insr 



cording to the colour of the precipitate they form with 
iron salts. This difference is evidently one of constitu 
tion, for, as Stenhouse* first showed, one group of tannin 
can be converted into gallic acid and yield pyrogallol, 
whilst the other group does not give these reactions. 

Thus, when heated to 160 C., different products of 
decomposition are formed, the " iron-blueing " tannins, of 
which gallotannic acid may be taken as the type, yielding 
metagallic acid and pyrogallol, whilst the " iron-greening " 
tannins produce metagallic acid and catechol. 

Thorpe's method of preparing pyrogallol by heating 
gallotannic acid in glycerin has been used as a qualitative 
test of the nature of the tannin : I grm. of the tannin 
is slowly heated to 160 C. in 5 c.c. of glycerin, and the 
temperature then raised to 200-210 C. for 20 minutes. 
The liquid is then diluted with 10 c.c. of water and ex- 
tracted with an equal volume of ether (or extracted with 
ether without previous dilution, Trimble), and the residue 
from the ethereal extract dissolved in water and tested for 
pyrogallol or catechol by the following tests : f 



Reagent. 


ryrogallol. 
i per ceiit. solution. 


Catechol. 
I per cent, solution. 


Ferric chloride . ; 
Ferric acetate . - . 
Lime water 
Pinewood moistened 
with hydrochloric 
acid 


Ked, turning brown. 
Dark purple. 
Purple, then brown. 

No change. 


Green colour. 

1 5) 

Clear red. 
Violet colour. 


Melting-point . 


131 c. 


mC. 



* Mem. Chem. Soc., 1842, i. 133. f Trimble, The Tannins, i. p. 26. 






TANNIN MATERIALS FOR INKS 



51 



When a tannin is heated with dilute hydrochloric acid 
(2 per cent.) in a sealed tube at 100 C. an insoluble 
precipitate of ellagic acid (crimson colour with nitric acid) 
may be formed. 

When boiled with nlkalies the ''iron-greening" tannins 
yield protocatechuic acid and phloroglucinol, or acetic acid, 
whilst the "iron-blueing" tannins are converted into 
gallic and ellagic acids. 

The elementary composition of the different tannins has 
been suggested by Trimble * as a possible means of clas^i- 
fication. Thus, the gall tannins, or "iron-blueing " group, 
contain about 52 per cent, of carbon and about 3-5 per 
cent, of hydrogen, whilst the "iron-greening" tannins 
have 60 per cent, of carbon and 5 per cent, of hydrogen, 
e.g. : 

Group I. 





Carbon. 


Hydrogen. 




Per cent. 


Per cent. 


Gallotannic acid . 


52.10 


3-52 


Chestnut wood tannin . 


52.11 


4.40 


Chestnut bark tannin . 


52.42 


4.67 


Chestnut tannin (Xa*s) . , 


52.07 


3-97 


Sumach tannin (Lotve) . 


52.42 . 


3-56 



Group II. 





Carbon. 


Hydrogen. 




Per cent. 


Per cent. 


Oak-bark tannin (av. of 9) . 


59-79 


5.08 


Kino tannin (Bergltolz) 


59-65 


, 4-87 


Oak-bark tannin (Etti) .... 


59-25 


4.99 


Catechu tannin (Lowe] .... 


61.93 


4.80 


Tormentilla tannin (lie/nbold) 


60.75 


4.65 



The tannins in Group I. give a white precipitate, chang- 
ing to blue with lime water, whilst in the case of the 
tannins in Group II., the colour of the precipitate is light 

* The Tannins, ii. p. 132. 



52 INKS AND THEIR MANUFACTURE 

pink, changing to red or brown. Bromine water precipi- 
tates the tannins in the second group, but not those of the 
first group. 

Suitability of Tannins for Ink-making. Only the 
" iron-blueing " tannins are suitable substances for the 
manufacture of black ink, as has been shown by SMuttig 
and Neumann* who found that mixtures of extracts of 
pine, cafcechu, quebracho, kino, and hemlock with solutions 
of iron salts gave bright green colorations on paper, but 
after six months' exposure only rust-like stains were 
left. 

Good black inks can be prepared from algarobilla, divi- 
divi, myrobalans, valonia, and sumach, all of which contain 
" iron-blueing " tannins. 

Oak-bark tannin, although an "iron-greening" tannin, 
also contains a substance giving a blue precipitate with 
iron salts, and can therefore be used in the manufacture of 
ink (vide infra). 

The most important of the tannins suitable for ink are 
described individually in the following pages. 

CHESTNUT BARK AND WOOD. 

The Spanish, or Sweet Chestnut (Castanea vesca), is a 
large tree, frequently 80 feet or more in height, which 
grows abundantly in the countries surrounding the Medi- 
terranean, and in sheltered districts as far north as Scot- 
land. In America it is common in many of the States as 
far west as Indiana. The fruit is the well-known chestnut, 
which is largely imported into this country. 

Chestnut Extract. An aqueous extract of chestnut 
wood or bark is prepared extensively in Pennsylvania and 
Virginia, the decoctions being subsequently evaporated to 
a solid mass. According to Trimble^ it is impossible to 
manufacture a good extract without the use of a vacuum 
pan. It is said to be frequently adulterated with molasses 
or glucose, and is itself employed to adulterate oak bark 
extract. 

* Die Eisengallustlnten, p. 38. 
f The Tannim; ii. p. 129. 



' TANNIN MATERIALS FOR INKS 



53 



Chestnut Tannin. Sheldon* who appears to have been 
the first to call attention to the value of chestnut wood as 
a tanning and dyeing material, asserted that it contained 
twice as much tannin as oak bark. 

Trimble (loc. ciL) found air-dried chips to contain 7.8$ 
per cent, of tannin, which is slightly higher than the 
amount found by Sheldon; whilst Simand\ found 8.5 per 
cent, in chestnut wood, and 23.52 per cent, in chestnut- 
wood extract of 31 Be., the determinations being made by 
Lowenthal's permanganate method. 

Nass^. was the first to prepare a tannin from chestnut 
wood, and to determine its composition and properties. 
The aqueous extract of the wood was fractionally precipi- 
tated with sodium chloride, and the final fractions dialysed 
and then extracted with acetic ether. 

In this way he obtained a white preparation which was 
soluble in water, alcohol, ether, and glycerin, and gave the 
following reactions when tested in a one per cent, solution. 



Reagents. 


Chestnut tannin. 


Gallotannic acid. 


Ferrous salt 


No change. 


No change. 


Ferric ammonium sul- 






phate 


Blue-black precipi- 


Blue-black precipi- 




tate. 


tate. 


Tartar emetic + ammo- 






nium chloride . 
Bromine water . 


Slight precipitate. 
No precipitate. 


Slight precipitate. 
No precipitate. 


Lime water . 


Light precipitate, be- 


White precipitate, be- 




coming light blue. 


coming light blue. 


Sulphuric acid (1:9) . 


No deposit on boil- 


No deposit on boil- 




ing. 


ing. 



When heated to 200 C. it was converted into pyrogallic 
and metagallic acids, and gave an acetyl derivative closely 
resembling that of gallotannic acid. 

Its elementary composition was also found to be very 
similar to that of gallotannic acid, as is shown by the fol- 
lowing results obtained by Nass and by Trimble : 

* A trier. Journ. Science, 1819, i. 313. 
f Dingler's polyt. Journ. 1885, cclv. 487. 

t Zeit. anal. C/iem., 1886, xxv. 134 ; also Trimble, The Tannins, ii. p. 
124. loc. cit., p. 127. 



54 



INKS AND THEIR MANUFACTURE 





Chestnut 
tannin 
(AVm). 


Chestnut 
wood tannin 
(Trimble). 


Chestnut 
bark tannin 
(Trimble). 


Gallotaunic 
acid. 




Per cent. 


Per cent. 


Per cent. 


Per cent. 


Carbon . 


52.20 


52.42 


52.11 


52.17 


Hydrogen 


3-97 


4.67 


4.40 


3.10 



In Trimbles opinion this similarity in composition and 
reactions renders it highly probable that chestnut tannin 
is identical with the gallotannic acid from galls. 

Ink from Chestnut Wood. Sheldon (loc. cit.) in 1819 
found that chestnut wood contained ^ as much substance 
giving a black coloration with iron (i.e., tannin), as was 
present in logwood (hgernatoxylin). He stated that it was 
probably unequalled as a material for ink, since it gave 
ii rich blue-black colour with iron, whilst galls or sumach 
used in the same proportion had a redder shade. The ink 
formed by chestnut decoction was blue, but on paper it 
dried, yielding an intense black. The permanency of the 
ink was tested by exposing the writing to the sun and air, 
and was found highly satisfactory. 

Schluttig and Neumann* however, in their comparative 
tests on the stability of inks prepared from different 
tannin materials, found that chestnut iron-ink, originally 
blue-black, was fainter than the ink from most of the other 
"iron-blueing" tannins (p. 50). 

In 1825 Giroud took out a patent (Eng. Pat. No. 5285) 
for a substitute for galls, to which he gave the name of 
" damajavag." This was prepared by soaking I cwt. of the 
wood of the chestnut tree, or shells of the nut, with water 
for twelve hours, and then boiling it with 180 to 200 quarts 
of water and evaporating the decoction to a paste, which 
was to be used in the manufacture of ink, or in tanning. 

An ink prepared by us from chestnut extract had a good 
blue-black colour. On standing exposed to the air for a 
month it yielded a deposit containing 7.37 per cent, 
of iron. 

* loc. cit. p. 38. 



TANNIN MATERIALS FOR INKS 



55 



SUMACH. 

Sumach or Sumac is the name given to the leaves of 
various plants belonging to the natural order Elms. 

Of these the Sicilian sumach, Rims coriaria, grows wild 




Fig. 23. Sumach (Coriaria myrtifolia) . 

in Spain, Portugal, and other Mediterranean districts, and 
is also widely cultivated in these countries. The most 
esteemed variety of Sicilian sumach, known as Alcamo, 



56 INKS AND THEIR MANUFACTURE 

occurs in commerce as a light green powder with an 
aromatic odour. A second and inferior variety, which is 
chiefly used in dyeing, has a more yellow shade and con- 
tains less tannin. 

The best French sumach is very similar to that grown in 
Sicily. Another French variety, known as redou, is obtained 
from Coriaria myrtifolia (Fig. 23). 

In preparing sumach for the market, the branches are 
dried in the sun, and the leaves removed and ground to 
powder in mills. 

The leaves of the Venetian sumach, Ehus cotinus, a 
shrub cultivated in Italy and the south of France, contains 
a yellow dyestuff, and a tannin which gives an olive-green 
compound with iron salts, and is therefore unsuitable for 
ink-making. 

In America two species of Rkus, R. copallina and R. 
glabra, both of which contain much less tannin than Sicilian 
sumach, are extensively used as tanning materials. 

Sumach Tannin. The proportion of tannin in sumach 
varies considerably, but the usual limits are from about 
1 3 to 20 per cent. 

Stenhouse * was the first to show the similarity in com- 
position a::d properties between the tannin of sumach and 
gallotannic acid, both yielding gallic acid and pyrogallol. 
The percentage composition of his sumach tannin was: 
Carbon, 49.73 to 50.12; hydrogen, 3.64 to 376; and 
oxygen, 46.24 to 46.5 I. 

Lowe + obtained a purer product by extracting Sicilian 
sumach with alcohol, treating the residue from the extract 
with water, extracting the tannin by means of acetic acid, 
and purifying it by repeatedly dissolving it in water, and 
precipitating it with sodium chloride. Gallic acid (which 
was not identified) would be left in solution in the sodium 
chloride treatment. 

Lowe confirmed Stenhouse's statement of the formation 
of gallic acid from the tannin. Crystals of the latter were 
obtained by heating the tannin solution either alone or 
with 2 per cent, of sulphuric acid for several hours in a 
sealed tube placed in a brine bath. 

* Mem. Chem. Soc., 1842, i. 135. 
f Zeit. anal. Chem., 1873, xii. 128. 



TANNIN MATERIALS FOB INKS 57 

The properties of the Sicilian sumach tannin were 
found to be identical with gallotannic acid, and analysis 
showed them to have the same composition, corresponding 
with the formula C 14 H 10 9 . 

Lowe was doubtful whether the tannin of other species 
of sumach could also be regarded as identical with gallo- 
tannic acid. Thus a tannin prepared from Tyrol sumach 
contained 52.3 per cent, of carbon and 3.8 per cent, of 
hydrogen, corresponding with the formula C 16 H^0 10 . 
Moreover, this tannin differed from that of Sicilian 
sumach in not yielding gallic acid when heated in a sealed 
tube with sulphuric acid. 

Sumach contains a small quantity of a yellow dyestuff, 
quercetrin. 

Ink from Sumach. As the tannin of sumach is 
identical, or at least allied to that of galls, it was 
to be anticipated that it would yield an ink of a very 
similar character, only modified slightly by the colouring 
matter of the leaves. In fact, Ribeaucourt * found that 
the ink made from it had a greenish shade. 

Lewis A who made experiments in 1763 with sumach as 
an ink material, came to the conclusion that it was inferior 
to galls as a source of tannin. 

Schluttig and Neumann^ however, have shown that 
sumach iron-ink is but little inferior in durability to ink 
prepared from Chinese galls, and superior to "Knop- 
pern " ink. According to Viedt,^ ink is occasionally pre- 
pared from sumach on a manufacturing scale. 

DIVI-DIVI. 

Dim-dim is the name given in commerce to the dried 
pods of the South American shrub, Ccesalpinia coriaria 
(Fig. 24), which was not known in Europe until the latter . 
halt' of the eighteenth century. It grows in low-lying 
marshy lands, attaining a height of twenty to thirty feet. 

The pods are of a dark brown colour, and about one and 
a half to three inches in length. They have a very astrin- 

* Ann. de Cltlm., 1792, xv. 156. 

f loo. tit. p. 382. J loc. tit. p. 38. 

Dingier' s polyt . Journ., 1875, ccxvi. 453. 



58 INKS AND THEIR MANUFACTURE 

gent taste, due to the tannin, which is for the most part 
concentrated in the rind immediately beneath the epi- 
dermis. The recorded amount of tannin ranges from 30 
to 52 per cent. A commercial sample examined by us 
contained 36 per cent. 

Divi-divi Tannin. Stenhousc * separated a tannin from 
divi-divi, which he found to have the following com- 
position : Carbon, 50.12 ; hydrogen, 3.72: and oxygen, 
4.62. 

This tannin yielded gallic acid and pyrogallol, and 




Fig. 24. Divi-divi pods. 



formed deep blue insoluble compounds with ferric salts, 
and was thus very similar in composition and properties to 
gallotannic acid. 

In a more extended research, Lowe | found that the 
tannin of divi-divi behaved with most reagents like gallo- 
tannic acid, from which it was distinguished, however, by 
yielding a deposit of ellagic acid when heated in aqueous 
solution in a sealed tube. 

He therefore described this tannin as ellagitannic acid, 

* Mem. Cliem. Soc., 1842, i. 141. 
f Zeit. anal. Client., 1875, xiv. 35. 



TANNIN MATERIALS FOR INKS 59 

and ascribed to it the formula C 14 H 10 10 , which maylDe 
regarded as gallic acid, C 14 H 12 10 , minus 2 atoms of 
hydrogen, or gallotannic acid, (J u tT 10 O 9 , plus I atom of 
oxygen. 

Lowe, also found the same tannic acid in myrobalans. 

A specimen of divi-divi examined by us contained 
34 per cent, of tannin determined colorimetrically, and 
expressed in terms of gnllotannic acid. 

Ink from Divi-divi. Stenhouse (loc. cit.) states that 
calico printers had attempted to use divi-divi as a sub- 
stitute for galls, but had not found it satisfactory, owing 
to the large proportion of other extractive matters (gums). 





Fig. 25. Myrobalans. 

In the case of ink this would not be so objectionable, 
and in fact Viedt * asserts that divi-divi is sometimes used 
in Germany as a source of ink-tannin. 

An ink was prepared by us from an extract of divi-divi 
(5 grms.), treated with I grm. of ferrous sulphate. The 
deposits yielded by this ink contained from 6.77 to 7.77 
per cent, of iron. 

MYROBALANS. 

The dried fruit of different species of Terminalia grow- 
ing in India and the East Indies is sold as a tanning and 
dyeing material under the name of myrobalans (Fig. 25). 

The ripe fruit weighs between 5 to 10 grms., and has a 
very astringent taste, due to the tannin in the husk. 
* Dingier 's poly 't. Journ., 1875, ccxvi. 453. 



60 INKS AND THEIR MANUFACTURE 

The Indian species, T. chebula, which yields the 
" black " or " chebulic " myrobalans of commerce, is exten- 
sively used in conjunction with iron salts as a black dye, 
and is also employed in the manufacture of ink. 

The earliest mention of the possible use of myrobalans 
as a substitute for galls is that made by A. Johnson * in a 
communication to the Society of Arts in 1 80 1, in which 
he stated that the natives in India used them to give a 
black colour to leather, mixing the powder with iron 
filings and water. 

A committee of the Society appointed to report on the 
subject found that the pulp and outer husk of the fruit 
gave a rich black colour with ferrous sulphate. 

Ink prepared by us from myrobalaus was of a good 
blue black colour, and yielded insoluble deposits containing 
about 6 per cent, of iron. 

The Tannin of Myrobalans. Loii'e\ found about I per 
cent, of gallic acid in myrobalans, and extracted a tannin 
which contained 49.42 per cent, of carbon and 3.16 per 
cent, of hydrogen, corresponding with the formula 

Ci 4 H 10 10 . 

When heated in a sealed tube at io8-uo C., a 
solution of this tannin yielded a deposit of ellagic acid ; 
and from this fact and the elementary analysis, Lowe con- 
cluded that it was ellagitannic acid, identical with that of 
divi-divi. 

Z'6lffel\ confirmed Lowe's statement of the occurrence of 
I per cent, of gallic acid, but found that the tannin was a 
mixture of ellagitannic acid, and a glucoside of gallotannic 
acid, the former being in the greater proportion. 

A specimen of myrobalans examined by us was found 
to contain 39 per cent, of tannin determined colorimetric- 
ally, and expressed in terms of gallotannic acid. 

VALONIA. 

Valonia is the commercial name for the acorn cups of 
certain species of oaks growing in Asia Minor and different 

* Trans. Soc. Arts, 1801, xix. 343. 
t Zeit. anal. Chem., 1875,^1^. 35. 
J Arch, der Pharm., 1891, cCxxix. 155. 



TANNIN MATERIALS FOR INKS 

the most important are 



61 



parts of Greece, of which 
cegilops and Q. macrolepis. 

The best sorts are gathered before the fruit is quite 
ripe in April, those beaten from the trees in September 
and October being poorer in tannin. 

The cups (containing the acorns) are first partially dried 
on the ground and then conveyed by mules to Smyrna, 
where they are stored in warehouses until slight fermenta- 
tion sets in and causes the acorns to fall from the cups. 









Fig 26. Valonia. 

If exposed to rain after gathering, the acorn cups turn 
black and lose a considerable amount of tannin by 
fermentation. 

As met with in commerce valonia consists of semi- 
circular prickly backed cups, about 50 mm. in diameter 
(see Fig. 26). 

The amount of tannin they contain varies greatly with 
the district, species of oak and time of collection, but 
usually ranges from about 20 to 45 per cent. 



62 INKS AND THEIR MANUFACTURE 

The following percentages have been recorded inter 
aha: 32.4 (Handtke); 38 (Gallow); 22.6-39.2 (Rothe) ; 
and 31.6 to 35.64 (Simand). 

Eitner* examined eighteen samples of different origin 
of the harvest of 1886, and found them to yield from 
42.4 to 51.9 per cent, of total extract, 1.6 to 3 per cent, 
of soluble ash, and 21.28 to 30.2 per cent, of tannins. 

The best valonia is that obtained from Smyrna, the 
Greek and Albanian products being held in much smaller 
esteem. 

In 1852 the prices per cvvt. were as follows : Smyrna, 
143. to 155. ; Morea, ics. to I2s. ; and Camata, 145. to 165. 
(Tomlinsori). The prices given by Procter in 1885 were 
considerably higher, viz., Smyrna, I2s. 6d. to 2Os. 6d. ; 
Morea, IDS. 6d. to iSs. 6d. ; and Camata, 155. to igs. 
per cwt. 

The Tannin of Valonia. This appears to be mainly 
ellagitannic acid, judging by the results of Bottinger* 
who extracted the tannins from valonia, divi-divi, and 
algarobilia, and prepared the acetyl derivative of each. 
The amount of acetyl in the valonia tannin (44.1 per 
cent.) was nearly the same as that of divi-divi (43.19 per 
cent.) and algarobilia (43.9 per cent.), and hence Bottinger 
concluded that the preparations were identical in com- 
position. 

In the colorimetric estimation of the amount of tannin 
in terms of gallotannic acid we found the solution yielded 
a much bluer tinge than the standard solution of gallo- 
tannic acid, and it was necessary to add a slight trace of 
an aniline colour to the latter, in order to match the tint. 
In duplicate determinations we found (i) 59.1 per cent, 
and (2) 57.5 per cent. The amount found by Procter's 
hide powder method was 20 per cent., so that the tannin 
in valonia appears to have a greater tinctorial value than 
gallotannic acid. The filtrate from the hide powder con- 
tained iron-colouring substances (gallic acid), correspond- 
ing to 2.5 per cent, of gallotannic acid, 

Ink from Valonia. Vaionia yields a very rich bluish 
black ink, and appears to us to be a very suitable raw 

* Dcr Gerlet; 1887, xiii. 18. 

-f Bcr d. d. cJiem. &e$., 1884, xvii. 1503. 



TANNIN MATERIALS FOR INKS 63 

material for the manufacture, especially if used in 
admixture with Chinese galls. 

The deposits yielded by the ink on exposure to the air 
are very similar to those given by gall or divi-divi inks. 
Thus the deposits examined by us contained from 11.5 
to 12.8 per cent, of iron oxide. 

OAK-BARK TANNINS. 

Owing to the fact that infusions of oak bark give a 
blue coloration with iron salts the tannins present were 
formerly regarded as identical with gallotannic acid. 
This error was first pointed out by Stenhouse* who showed 
that an infusion of oak bark differed from a solution of 
gallotannic acid in not yielding gallic acid or pyrogallpl. 

In 1867 Ghraboivshi found that instead of gallic acid an 
amorphous red compound, " oak red," was produced, 
which Etti\ obtained by boiling an oak tannin with 
dilute sulphuric acid, and concluded to be an anhydride 
with the formula 2C 17 H 6 9 -H 2 = C 34 H 26 5 . 

An extended series of researches on the oak tannins 
were the'n made independently by JStti, by Lowe, and by 
Bottinger, but the most conflicting results were obtained. 
Thus Etti prepared an oak tannin which did not dissolve 
in water and gave a green coloration with ferric salts, 
whilst Lowe obtained soluble tannins with the formulae 
C 28 H ?8 14 and C 28 H 30 15 , which gave blue precipitates 
with iron solutions. 

Trimblel has given an excellent summary of these 
different results, though without succeeding in reconciling 
them. He himself has made numerous preparations, and 
has found the average composition of nine of these to be 
as follows : Carbon, 59.79; hydrogen, 5.08; and oxygen, 
35.13 per cent. results which correspond best with the 
formula of Etti's tannin, C 20 H 20 9 . 

In Trimble's opinion there is no question but that oak 
tannins give green colorations with iron salts, and he 
attributes the blue colorations given by oak-bark infusions 

* Mem. Chem. Soc., 1842, i. 140. 
t Monatsh.f. Chem., 1880, i. 262. 
j The Tannins, ii. p. 90* 



64 INKS AND THEIR MANUFACTURE 

to the presence of an associated colouring-matter. In the 
case of the chestnut oak he separated this " iron-blueing " 
compound by first precipitating the oak tannins with 
neutral lead acetate and then treating the filtrate with 
basic lead acetate. 

Reactions of Oak Tannins. On heating oak-bark 
tannins to 190 C. catechol is formed as the main decom- 
position product, whilst on fusion with caustic alkali 
protocatechuic acid is obtained. 

The colour reactions vary greatly with the species of 
oak whence the tannins were derived, which is evidence 
that they are not identical. 

Trimble* gives the following table of the reactions of 
the tannins separated from two species of oak bark com- 
pared with those given by gallotannic acid : 



Keagent. 


English oak, 
Q. robur. 


Indian oak, 
Q. sessiliflora. 


Gallotannic 
acid. 


Copper sulphate. 
Copper sulphate + 
ammonia. 


Precipitate. 
Red brown preci- 
pitate. 





No precipitate. 
Brown precipi- 
tate. 


Stannous chloride 
and HC1. 


Violet colour. 


Violet colour. 


Slight green 
colour. 


Sodium sulphite. 
Bromine water. 
Ferric chloride. 

Ferric chloride + 
ammonia. 


Pink colour. 
Yellow precipitate. 

Blue green colour 
and green preci- 
pitate. 
Purple bi*own pre- 
cipitate. 


Yellow colour. 

Yellow precipi- 
tate. 
Green colour aud 
precipitate. 

Purple brown 
precipitate. 


Slight pink 
colour. 
No precipitate. 

Blue colour and 
precipitate. 

Purple precipi- 
tate. 


Ferric ammonium 
sulphate. 


Blue green colour 
and green preci- 
pitate. 


Green colour and 
precipitate. 


Blue colour and 
precipitate. 


Lime water. 


Precipitate turning 
pink. 


Precipitate turn- 
ing pink. 


Precipitate turn- 
ing blue. 



Amount of Tannins in Oak Bark. Procter gives the 
proportion of tannins in European oak bark as IO to 12 
per cent, whilst Trimble* found the bark of different 

* loc. cit. ii. p. 48. 



TANNIN MATERIALS FOR INKS 



65 



species of American oaks to contain from 4.04 to 14.21 
per cent., whilst an English oak bark gave 12.37 P er cent, 
calculated on the dry substance. 

The chief species of oak from which the commercial 
bark is derived are Q. pedunculata, sessifl>ora, and rubescens, 
the first of which usually contains more tannin than the 
others. 

Eitner* has shown that the amount of tannin varies 
with the season. Thus in the case of the bark from Q. 
pedunculate he obtained the following results : April, 
14.80; May, 10.71 ; June, 12.33; July, 9.8 ; and August, 
1 1.23 per cent. 

Weiss f analysed commercial oak barks of different 
origin with the following results : 





Tannin. 


Ash. 


Origin. 


Per cent. 


Per cent. 


Hungarian (3) 


10.36-13.47 


5.68-7.31 


. German (3) 


11.87-16.18 


6.27-8.52 


French (3) . 


13.82- 16.22 


6.14-7.77 


Danish (3) . 


13.86- l6.22 


6.66-7.81 


Swedish 


12.02- 14.59 


5-55-7-05 


Average . 


13-5 


6.82 



Ink from Oak Bark. Stenhpuse (loc. cit.) found that 
a good blue-black ink could be prepared from an infusion 
of oak bark, in which respect it differed from the infusions 
of kino, larch, and alder barks, which only gave green 
colorations with iron salts. 

According to Prechtl,% oak bark was used fifty years ago 
in conjunction with other substances in the manufacture 
of ink. Thus he gives the following formula for the pre- 
paration of ink from oak-bark galls and Knoppern : Galls, 
9 Ibs., logwood i Jibs., rasped oak bark, 81bs., Knoppern 
61bs., gum 2lbs., ammonium chloride Jib., infused in 40 
quarts of water and 24 quarts of vinegar, and the infusion 
mixed with ferrous sulphate. 

* Der Gerber, iv. 85. 
t Ibid. 1885. ii. 181. 
I TechnoL Encijclop.. 1852, xviii. 460. 



66 INKS AND THEIR MANUFACTURE 

Since the pure oak tannins are "iron-greening" sub- 
stances, whilst the blue-black colour given by oak-bark 
infusions with iron salts is only due to the presence of an 
associated substance (vide supra), the use of oak bark for 
ink is not economical. Moreover, ink prepared exclusively 
from the infusion has been shown by Scliluttig and Neu- 
mann* to be somewhat less stable on exposure to light 
and air than the inks from galls, divi-divi, or other sub- 
stances containing " iron-blueing " tannins. 

GALLOTANXIC ACID. 

The tannin which is best known is that contained in 
galls, and to this the name of gallotannic acid has been 
given to distinguish it from quercitannic acid and other 
tannins. It is present in Aleppo, Chinese, and Japanese 
galls and in Knoppern, and has also been identified in 
sumach, myrobalans, and algarobilla. 

Pelouze f prepared gallotannic acid by extracting pow- 
dered gall with ether containing water, and showed that 
on exposure to the air in an aqueous solution it gradually 
yielded an insoluble deposit consisting mainly of gallic 
acid. 

Strecker^ came to the conclusion that gallotannic acid 
was a glncoside, which was decomposed on fermentation 
in accordance with the equation 

C, 4 H 28 0.> 2 - C 6 H 12 6 + 2C 14 H 10 9 - H,0 
Glncoside. Glucose. Taimic acid. 

Subsequently it was shown by Scliiff^ thai perfectly 
pure gallotannic acid was free from glucose, and was an 
anhydride containing two gallic acid groups, i.e., digallic 
anhydride. In his opinion the glucose in Strecker's pre- 
paration was originally present in the galls, and had been 
extracted simultaneously with the tannic acid. 

Trimble || concludes that although gallotannic acid can 
be so purified as to be eventually only digallic anhydride, 

* Die Eisengallnxtintcn, p. 38. 

j Ann. Chem. P/tanit., 1833, liv. 337. 

j Ibid. 1854, xc. 238. 

Ibid. 1873, clxii. 43. 

i| The Tannins, i. p. 29. 



TANNIN MATERIALS FOR INKS 67 

it is rarely if ever met with in that state in the '* pure " 
article of commerce, which contains variable amounts of 
glucose in a loose state of combination. In his opinion 
the commercial article must be regarded either as a gluco- 
side of digallic acid, or as a mixture of the glucoside and 
of the pure anhydride. 

Sdiiff (loc. cit.) prepared a pentacetyl derivative of gallo- 
tannic acid, which melted at 137 0., and had a composi- 
tion agreeing with the formula C 14 H 5 (C 2 H 3 0) 5 O a . 

This compound was insoluble in water and cold alcohol, 
and gave no coloration with iron salts. 

The following constitutional formula represents the for- 
mation of this acetyl derivative, and also the formation of 
gallic acid by the hydration of the gallotannic acid : 

OH, ,OH 

OH/ ! \COv 
OH V - , ' / 



Fermentation of G-allotannic Acid. Chevreul showed 
that by keeping a solution of gallotannic acid in a sealed 
tube so as to exclude atmospheric oxygen, it could be kept 
unchanged for an indefinite period. 

It has frequently been asserted (e.g., by Viedt, p. 43), 
that the conversion of gallotannic acid is due to the action 
of an oxidising enzyme. It was shown, however, by van 
Tieghem * that this was not the case, but that the spon- 
taneous change was due to the action of two mould fungi, 
Penicillinm glaucum and Aspergillus niger in the presence 
of air. By inoculating solutions of gallotannic acid with 
the spores of these fungi, he was able to effect a complete 
conversion of that substance into gallic acid in a few days. 
The fermentation only took place within the liquid, for 
when there was only a surface growth a very small amount 
of gallic acid had been produced after several days' vigorous 
fermentation. From the results of Saccs t experiments it 

* Complex Itc/idt/*, 1867, Ixv. 1091. 
t Hrid. 1871, Ixxii. 766. 



68 INKS AND THEIE MANUFACTURE 

would seem that ordinary yeast also possesses the hyclro- 
lysing property of these two ferments. 

Properties of Gallotannic Acid. Gallotannic acid is 
a yellowish- white, glistening, amorphous powder, which is 
readily soluble in water, alcohol, and ether. 

When heated with dilute acids (Stenlwuse) or fermented 
[vide supra) it takes up water and is converted into gallic 
acid, whilst when boiled with alkaline solutions it yields 
gallic and ellagic acids. When heated alone to 160 C. it 
is decomposed and yields a sublimate of pyrogallol (see 
p. 50). 

Gallotannic acid gives dark violet or blue precipitates 
with iron salts. It is precipitated quantitatively by lead 
salts, with which it yields white compounds, and it forms 
white unstable gelatinous precipitates with antimony. It 
combines with gelatin to form an insoluble compound 
(leather). 

GALLIC ACID. 

Gallic acid (C 7 H 6 O,. + H.,0), which was discovered by 
Sckeele, is present naturally in small proportion in various 
vegetable substances, such as tea, galls, and myrobalans 
(about i per cent.). 

It is obtained from gallotannic acid by fermentation 
with certain mould fungi (p. 43), or by the hydrolysing 
action of dilute acids : 

C 14 H 10 9 + H,0 = 2C 7 H 6 B . 

Its constitutional formula shows that it may be regarded 
as benzoic acid, in which three atoms of hydrogen are 
replaced by hydroxyl groups : 

C 6 H,(OH), . COOH + H 2 0. 

Properties. Gallic acid crystallises in white silken 
needles, which melt above 200 C. It is much less soluble 
in water than is gallotannic acid, I part requiring 130 
parts at 12.5 0. to bring it into solution. 

It is more soluble in absolute alcohol, 100 parts of 
which at 15 C. dissolve 27.95 parts, whilst 100 parts of 
ether at the same temperature only dissolve 2.5 parts. 

When heated alone to about 215 C. it is decomposed 



TANNIN MATERIALS FOR INKS 69 

with the formation of pyrogallol (C H 3 . (OH) 3 ) and 
water. 

When heated with sulphuric acid at 100 C. it gives off 
red vapours of rufigallic acid, whilst under the influence 
of arsenic acid at a high temperature it yields ellagic acid. 

It combines with alkalies to form salts, which, in alka- 
line solution, absorb oxygen from the air and turn brown. 

Ferric salts are reduced by gallic acid with the formation 
of blue-black compounds containing iron in the ferrous 
condition (Chevreul). 

Ferrous sulphate free from ferric salts gives no colora- 
tion with gallic acid, but ferric sulphate gives a blue colour 
and eventually a precipitate ( Wackeiibrodcr). 

Unlike tannic acids, gallic acid yields no insoluble 
compound with gelatin. 

Various formula? for the preparation of ink from gallic 
acid are given on pp. 96-98. 

Reactions distinguishing between G-allotannic and 
Gallic Acids. It has been generally accepted that tannic 
acid gives black precipitates with ferric salts, and no 
coloration with ferrous salts,* but Ruoss^ has recently 
shown that these statements are incorrect. He has found 
that tannic acid gives a black precipitate with ferric 
acetate, and a black precipitate or coloration with ferrous 
acetate. 

Moreover, he has also proved that on adding a solution 
of a ferric salt drop by drop to a solution of tannic acid 
only a dark coloration (and no precipitate) is obtained, 
the iron tannate being readily soluble in an excess of 
tannic acid. Since gallic acid behaves in the same way, a 
dark coloration with ferric salts is inconclusive. 

Rnoss has therefore devised the following two new re- 
agents, which he has found to be both characteristic and 
very sensitive : 

Ruosss Reagent /. (i) solution of 20 grms. of ferric 
sulphate per litre ; (2) solution of 28 grms. of crystalline 
sodium carbonate per litre ; (3) acetic acid (sp. gr. 1.04), 
containing 5 grms. of sodium tartrate per litre. 

The tannin solution is diluted to such an extent that on 

* /-'.'A? Schluttig and Neumann, lot', fit. p. 18. 
j /e'^. anal, ('hem., 1902, xli. 725. 



70 INKS AND THEIR MANUFACTURE 

adding the ferric sulphate solution drop by drop it still 
remains slightly transparent when the maximum colour 
has been reached. About 10 c.c. of such a solution are 
treated with the iron solution (i), which is added drop by 
drop until the colour ceases to become darker. The same 
number of drops of solution (2) are then added, and twice 
that quantity of solution (3). When the liquid is shaken 
and allowed to stand a black precipitate is obtained in the 
case of tannic acid, whilst gallic acid yields no such 
precipitate. 

The reaction is capable of detecting o.ooi per cent, of 
tannic acid. 

Ruoss's Reagent II. (i) a solution of 10 grms. of ferric 
sulphate + 15 grms. of sodium acetate + 1.7 grms. of 
sodium tartrate per litre; (2) a solution of 1.25 grms. 
of gelatin in 125 c.c. of hot water, made up to a litre with 
glacial acetic acid (sp. gr. 1.064). 

Ten c.c. of the tannin solution are treated with solution 
(i), added drop by drop until the colour ceases to darken, 
and then with the same quantity of solution (2). After 
being shaken and left for some time a flocculent blue- 
black precipitate indicates tannic acid. 

Rvoss's Oxidation Reaction* One drop of the ferric 
sulphate solution (20 grms. per litre) is added to 10 c.c. 
of the tannin solution, diluted as required in the test with 
Reagent I. A permanent dark coloration is obtained with 
tannic acid, whilst gallic acid gives a black coloration, 
immediately changing to yellow. 

If ferric acetate be used instead of ferric sulphate the 
dark coloration is permanent with gallic acid as well as 
with tannic acid. 

Gricssmayer' 1 s Reaction^ for tannic acid consists of 
adding one drop of a solution of tannin to a very dilute 
solution of iodine. The liquid becomes colourless, and on 
now adding a drop of a dilute solution of ammonia a 
blood-red colour is produced. 

Ruoss has pointed out that the reaction is also given by 
gallic acid, and is therefore inconclusive. 



* Ice. cit. p. 732. 

f Classen, HanttftHcJi dermal. Anal., p. 163. 



TANNIN MATERIALS FOR INKS 71 

Hydrogen Peroxide as a Reagent. It has recently been 
found by Mitchell and Hepworth that on adding hydrogen 
peroxide to a solution containing tannin and ferrous 
sulphate, there is an immediate black precipitate, the 
tannin being precipitated quantitatively, or nearly so, as 
a basic tannate ; whereas gallic acid treated in the same 
way yields a dark-brown solution, but only a slight trace 
of any insoluble compound. The precipitates yielded on 
ignition from 30 to 34.5 per cent, of ferric oxide, and thus 
approximated in composition to one of Ruoss's basic 
tannates (p. 79). 

We attempted to base a quantitative method of sepa- 
rating tannin on this reaction, but were unable to obtain 
concordant results. 



CHAPTER III. 

NATUKE OF INKS. 

CONTEXTS. Constitution of ink-forming- substances Influence 
of light and air Iron tannates Evidence of an inter- 
mediate blue iron oxide Tannates of iron Basic salts 
Methods of estimating tannates Procter's method 
Jackson's lead carbonate method Ruoss's ferric sulphate 
method Colorimetric methods Hinsdale's colorimetric 
method Mitchell's colorimetric method.. 

Constitution of Ink-forming Substances. The property 
possessed by gallic and tannic acids of forming blue com- 
pounds with ferric salts has been attributed by Schiff'* to 
the presence of free phenoloid hydroxyl groups, to which 
is also due the analogous colorations obtained with other 
compounds of the aromatic series. 

Thus, when a coloration is obtained with ferric chloride 
the presence of a free hydroxyl group may be inferred, and 
vice versa. 

F.OY instance, a violet coloration is given by phenol, 
salicylic acid, phenyl-sul phonic acid, &c. ; a Hue coloration 
by gallotannic acid, gallic acid, pyrogallol, arbutin, and 
many derivatives of tannic acid ; a green colour by ma&y 
tannins, resculetin, and parresculetin ; a red or reddish- 
ciolct colour by phloridziu, ty rosin, &c. ; whilst no colora- 
tion is obtained with picric acid, dinitro-hydroquinone, 
acetylgallic acid, &c. 

Schiff also came to the conclusion that the intensity of 
the colour stood in relation to the number of free hy- 
droxyl groups, the substances giving violet colorations 
containing only one free hydroxyl, whilst deep Hue-black 
colorations were produced by compounds containing 
several free hydroxyl groups. Thus, phenyl-sulphonic 

* Ann. ('hem. Pharm.. 1^71, clix. 164. 



NATUEE OF INKS 73 

/OH 
acid, C H H,<^ , gives a violet colour, whilst gallic 

\SO,.OH 
acid, C 6 H 2 (OII) 3 COOH, gives a blue-black colour. 

Scliiff's work was extended in a special direction .by 
Kostaneckiy* who investigated the relation between the 
constitution of certain organic dyestuffs and their tinctorial 
properties. He found that phenoloid colouring matters 
combine with oxide mordants when they possess two hy- 
droxyl groups in the ortho position. 

la a subsequent communication, Kostanecld f gave the 
name of " tinctogen group " to that atomic grouping which 
enables dyestuffs to combine with oxide mordants. 

The further question of the formation of permanent 
"inks" upon vegetable fibres was thoroughly studied by 
Sc.ldv.Uirj and Ncumann.l 

In ord?r to determine whether any phenol compound 
giving an intense coloration with iron salts was suitable 
for ink, they made a series of tests in which each substance 
was dissolved in water (with a little alcohol if required), 
and then treated with the same proportion of a solution of 
ferrous sulphate. 

The liquids were allowed to run down white paper 
stretched at an angle of 45, so as to form stripes 3 to 
6 mm. in breadth as in their " Stripe test " (p. 121), which 
were then allowed to dry. 

In the case of phenol, resorcin, hydroquinone, phloro- 
glucinol, orcin, triacet} 7 lgallic acid, trimethyl-pyrogallol, 
and some other compounds, nothing but a faint yellow 
stain due to iron oxide was obtained. 

On the other hand, dark violet colorations of varying 
intensity were given by gallic and tannic acids, pyrogallol- 
carboxylic acid, methyl and ethyl esters of gallic acid, 
potassium pyrogallol-sulphonate, and haematoxylin. 

From these and similar experiments Schluttig and Neu- 
mann established the fact that in order to yield colours 
forming a permanent ink on paper, the compound must 
contain three hydroxyl groups in juxtaposition. For 

* Bfti: (1. d. chem. GM.. 1887, xx. 3146. 
t I'titf. 1888, 3113, foot-note. 
J Die Eixengalluistutten, p. 16. 



74 INKS AND THEIR MANUFACTURE 

/OH 
instance, hydroquinone C G H 4 \ does not yield an ink, 

X OH 

whilst haematoxylin and gallic acid, each of which con- 
tains three adjacent hydroxyls, 

C 6 H 2 (OH) ;{ OH (i) 

Lr. n W JoH(2) 



Ha?aiatoxyliii, Gallic acid, 

give permanent colorations. 

The colour produced by the other substances were as 
resistant to the action of water, and in some cases (e.g., 
esters of gallic acid and haematoxylin) more resistant than 
the ordinary inks of gallic and tannic acids. 

Influence of Light and Air. On exposing stains given 
by the different compounds that formed inks for six weeks 
to the action of a current of air and bright sunlight, the 
following results were observed : 

Completely bleached. Colours of paroxybenzoic acid and 
ortho-carboxylic acid. 

Yclloivish-grey. Pyrogallol-sulphonic acid, tribrompyro- 
gallol, dibrom-gallic acid, and tannic acid. 

Dark, grey.- Monobrom-gallic acid, pyrogallol-carboxylic 
acid, and gallic acid. 

Dark, brown. Pyrogallol . 

Greenish, or Bluish-black. Pyrocatechin, protocatechuic 
acid, methyl arid ethyl esters of gallic acid, and haema- 
toxylin. 

From these results it appears that the inks of tannic and 
gallic acids are not the most permanent, but are far ex- 
ceeded in this respect by logwood (hsematoxylin) and other 
inks. 

The behaviour of tannic acid ink was remarkakle, for it 
was the faintest of the colorations in its group ; whereas 
if the accepted formula, in which there are five hydroxyl 
groups, of which three at least are adjacent (see p. 67), be 
correct, it should have been one of the darkest. ^ 

The stability of the inks was found to stand in propor- 
tion to their darkness on exposure. 



NATURE OF INKS 75 

Schluttig and Neumann consider that these experiments 
show conclusively that a determination of gallic or tannic 
acid in an ink (as prescribed by a German statute, p. 14), 
without reference to the presence of other compounds of 
the same character, is of no value as a test of the perma- 
nency of that ink. 

It has recently been shown by one of us (Mitchell)* that 
this law of atomic grouping, established by Scliluttig and 
Neumann, in the case of iron inks, also applies to inks con- 
taining ammonium vanadate in place of iron. 



IRON TANNATES. 

Compounds of Iron and Tannic Acid. Numerous 
metallic compounds of tannic acid have been prepared, but 
the iron salts are of primary importance in the manufacture 
of ink. Although nickel, cobalt and manganese are so 
closely allied to iron, it is remarkable that none of them 
forms an <c ink " with 'tannic acid. 

On adding a ferrous salt to tannic acid no coloration is 
at first produced, though under the influence of the atmo- 
spheric oxygen the liquid speedily becomes violet, then 
darkens into an ink, and eventually deposits a violet-black 
compound (vide infra). On the other hand, when a ferric 
salt is added to a solution of tannic or gallic acid reduction 
takes place, and ferrous iron can be detected in the liquid 
(ChevreuT). 

Evidence of an Intermediate Blue Iron Oxide. 
Berzelius concluded that in these changes a new acid of blue 
colour was produced, but Barresv:il t showed that the 
evidence pointed to the presence of compounds of tannic 
or gallic acid with an intermediate blue oxide of iron. 

Thus, on mixing ferrous and ferric sulphate, and imme- 
diately placing the mixture in sulphuric acid to eliminate 
water, a deep blue mass is obtained. An evanescent blue 
sulphate is also produced by evaporating a solution of the 
two sulphates nearly to dryness. Similarly by using 
crystalline sodium phosphate instead of sulphuric acid 



f, 1903. xxviii. 146. 
f Comptt* Ilcndu*. 1843. xviii. 739. 



76 INKS AND THEIR MANUFACTURE 

a deep blue iron phosphate is obtained. Barreswil was 
unable to isolate this blue oxide, but since the purest blue 
colorations were obtained with sulphuric acid, gallic acid, 
and sodium phosphate, when the mixture contained three 
equivalents of ferrous salt to two equivalents of ferric salt, 
he inferred that the hypothetical blue oxide had the com- 
position Fe 7 9 , or 3FeO . 2Fe 2 3 . 

Tannates of Iron. In 1833 Pelouze* studied the 
nature of the compound formed on adding ferric sulphate 
to a solution of tannin. The precipitate, when washed 
and dried at 120 C., yielded 12.0 per cent, of ferric oxide 
(= 8.4 per cent, of iron). 

Wittstein t prepared a series of insoluble compounds of 
some of which there is reason to doubt the individuality. 

1. On leaving a solution containing ij parts of tannin 
and one part of ferrous sulphate exposed to the air for a 
month, a precipitate with 8.40 per cent, of ferric oxide 
was obtained. This is apparently the substance formed 
when ink dries on paper (Hep-worth and Mitchell, infra). 

2. From a solution containing three parts of tannin to 
one part of ferric acetate a precipitate yielding 20.15 per 
cent, of ferric oxide was obtained. 

3. On diluting the dark blue solution a resinous pre- 
cipitate with 13.49 per cent, of ferric oxide resulted. 

4. Tannin solution added drop by drop to ferric acetate 
solution gave a precipitate yielding 50 per cent, of ferric 
oxide. 

5. On adding ferric acetate solution to a tannin solution 
the precipitate yielded 25 per cent, of iron oxide. 

Schiffl pointed out that the series of salts described by 
Wittstein might be grouped into two series, viz., those in 
which the hydrogen in a molecule of acid might be re- 
garded as being replaced by the monovalent group [FeO], 
and those in which several molecules of the acid gradually 
replaced the hydroxyl groups in ferric hydroxide 
Fe 2 (OH) c . 

* Ann. de GUI in. et Phys., 1833, liv. 337. 
t Jnhrexlier. (lei- Cheni., 1848, xxviii. 221. 
J Ann. Ghem. P/tarin.. 1875, clxxv. 176. 



NATURE OF INKS 



77 



Schifs Formula.' for the Iron Tannatcs of Pclouze and 
Wittstcin* 



Formula. 

! 


Iron 
calculated. 
Per cent. 


Ferric oxide 
calculated. 
1'er cent. 


Ferric oxide 
found. 
Per cent. 


C 14 H 9 (FeO)0 !( 

C 14 H 7 (FeO) 3 9 
C 14 H 6 (FeO) 4 !( 
C 14 H 5 (FeO) 5 0,, 
Fe(C 14 H 9 9 ) ;; 

Fe(C 14 H 9 9 ) :! 


14.21 

36.95 
41.36 

5.53 


20.3 
44.8 } I 

52.8 U 
58.99 J 1 

7-9 


20.15 
Wittstein 
prepared 
compounds 
containing 
42.8 to 56.3% 
8.4 
(Wittstein) 


Fe/ 


8.00 


...5 


12.0 

(Pelouze) 


Fe<^ W 
1 )C 14 H 8 B 
Fe/ 

x^O 


10.43 


14.9 


13.4. 14.9. 

S-4 

(Wittstein) 


Fe\ 


14.21 


20-3 


120.15 
(Wittstein) 


H0 \ C HO 








'!&% 


17-63 


25.2 


25.0 
(Wittstein) 



Scliijf considers it doubtful whether some of Wittstein' s 
gelatinous deposits were individual compounds, but at the 
same time points out that the agreement between the 

* See also a formula on p. 89, suggested by Schiff, which corresponds 
better with the amount of iron found by Withtein, and by Mitchell and 
Hepworth, 



78 INKS AND THEIR MANUFACTURE 

theoretical values and the results actually obtained is 
remarkable. 

Viedt * states that he has prepared an iron tannate 
consisting of 17.8 grms. of iron to TOO grms. of tannin, 
but gives no details of the analysis. 

Schliittig and Neumann's and Mitchell and HepwortJis 
experiments on the composition of the spontaneous de- 
posit from a solution of ferrous sulphate and tannic acid 
are described at length below. 

Basic Salts. Ruoss t has recently described a basic iron 
tannate, consisting of a previously unknown ferric tannate 
in combination with ferric hydroxide. 

This was prepared by treating a tannin solution with 
sodium carbonate solution, and adding ferric sulphate 
solution to the soluble sodium tannate formed. The excess 
of iron could be removed by treating the basic tannate 
with normal acetic acid, leaving the insoluble ferric 
tannate. 

This, when dried at 1 00 to 120 C., contained 15.0 per 
cent, of iron, as against 14.9 per cent, required by a 
tannate of the formula 

(C 14 H 7 9 ) Fe. 

Taking into consideration the formation of other basic 
salts, Ruoss subsequently came to the conclusion that it 
must be regarded as tannin in which the hydrogen of the 
carboxyl group was replaced by the monovalent .group 
[FeO], thus 

C 14 H 9 9 (FeO) = c ]4 H 7 9 Fe + H a O. 

Similar black basic salts, containing two, three, four, or 
five atoms of iron in the molecule, were prepared, but 
when more iron was introduced the colour became 
brownish-black. 

These salts may be regarded either as compounds of 
the normal tannate (C u H 7 9 )Fe, with ferric hydroxide, or 
as compounds in which the group [FeO] replaces hydro- 
gen, both in the carboxyl group and in the hydroxyl of 
the ferric hydroxide, e.g. 

(C 14 H 7 9 )Fe + 3 Fe(OH) 3 = (C 14 9 H 6 )(FeO) 4 + sH 3 0. 



* Dingier 1 * polyt. Journ., 1875, ccxvi. 456. 
j Zelt. anal. (item.. 1902, xli. 732. 



NATURE OF INKS 



79 



We give the amount of iron in these basic salts dried 
at IOO D 0., so that they may be more readily compared 
with the compounds of Wittstein and other earlier in- 
vestigators. 

Basic Tanneries of Ruoss. 











Formula. 


I roii. 
Per cent. 


Ferric oxide 1 . 
Per ceiit. 


Iron found. 
Per cciit. 


(C 14 H 7 9 )Fe 


14.9 


21.27 


15.0 


(C 14 H 7 9 )(FeO). 2 


24.42 


34.88 




(C 14 H 7 9 )(FeO) 3 
(C 14 H 6 9 )(FeO) 4 


31.40 
36.96 . 


44.85 
52-79 





(C 14 H 5 9 )(FeO) 5 


41.36 


58.99 





Since the composition of these basic salts varies with 
the concentration of the iron solution used for the pre- 
cipitation, Ruoss points out that they may also be regarded 
as merely mixtures of the normal tannate with ferric 
hydroxide. 

Ruoss has based a method of determining tannin upon 
its precipitation as the tannate (C 14 H 7 9 )Fe (vide infra). 

Iron Tannate precipitated ~by Hydrogen Peroxide. Hcp- 
irorth and Mitchell * investigated the nature of the tannate 
formed on adding hydrogen peroxide to a solution con- 
taining tannin and ferrous sulphate. There was an im- 
mediate dense black precipitate, which rapidly subsided, 
leaving a colourless solution. The precipitates thus 
obtained, when dried at 100 C., were found to contain 
from 21 to 22.5 per cent, of iron, and were probably basic 
tannates. 

Gallic acid treated in the same manner yielded only a 
very slight deposit, but the colour of the solution changed 
to dark reddish-brown. 

Attempts to base a quantitative method of determining 
gallotannic acid on this reaction have so far proved 
unsuccessful. 

* Unpublished results. 



80 INKS AND THEIR MANUFACTURE 

METHODS OF ESTIMATING TANNIN. 

The methods of determining tannins are very numerous, 
aud attempts have been made to utilise most of the reac- 
tions that seemed likely to give anything approaching 
quantitative results. Thus precipitation with gelatin and 
with all kinds of metallic salts have been tried, but the 
results of different observers have been far from con- 
cordant, which must be largely attributed to the fact that 
there are numerous tannins, and that these vary in their 
behaviour with different chemical reagents. 

For valuation of tannin materials for leather manu- 
facture the methods chiefly used are LwventhaV s method, 
which is based on the reduction of potassium per- 
manganate by tannins, and Procter's method, which 
depends on the absorption of the tannin by purified hide 
powder. 

In the permanganate method an aqueous solution of 
the tannin material is first titrated with potassium per- 
manganate solution with indigo carmine as indicator to 
obtain a valuation of all the reducing substances present. 
The tannin is then precipitated by means of gelatin, and 
the filtrate again titrated, the difference between the two 
results giving the amount of tannin in terms of potassium 
permanganate. The method will thus give the relative 
tanning value of two samples of the same kind of material, 
but numerous precautions are essential ; for the speed of 
titration, strength of the solution, and other factors, have 
an influence on the results. This method, which does not 
estimate gallic acid or other compounds (other than 
tannin) that give a coloration with iron salts, is an un- 
suitable one for the valuation of tannin material for ink 
manufacture. 

Procter's Method. We have found Trimbles * appa- 
ratus (Fig. 27) a very simple and satisfactory one for the 
determination of tannin by Procter's method. This con- 
sists of a cylinder of about 500 c.c. capacity, and a funnel- 
shaped tube about 18 cm. in length, and 2.5 cm. in width 
at the bottom, whilst the other end tapers to a fine tube 

* The Tannins, ii. p. 98. 



NATURE OF INKS 



81 



on which is fixed a piece of flexible rubber tubing to form 
the other limb of the siphon. 

A small piece of cotton wool is pushed lightly down to 
the narrow end, and the tube then loosely packed with 




Fig. 27. Trimble's apparatus for tannin determination. 

8 to 10 grms. of purified hide powder, and the opening 
closed with a large piece of cotton wool. 

The tannin infusion is poured into the cylinder a little 
at a time, so as to gradually moisten the hide powder. 
After standing for about two hours the liquid is gently 
siphoned through the indiarubber tube, the first 30 to 



82 



INKS AND THEIR MANUFACTURE 



40 c.c. being rejected. Fifty c.c. of the filtrate are then 
evaporated to dryness on the water-bath, the difference 
between the weight of the residue and that previously 
obtained by evaporating 50 c.c. of the tannin before the 
filtration giving the amount of tannin absorbed by the 
hide. 

Trimble obtained results by this method higher than 
those given by the permanganate and alum gelatin 
methods. 

The method should be employed by the ink manufac- 
turer in conjunction with a colorimetric one. 

Jackson's Lead Carbonate Method.* This is based 
upon Jackson's determination that a I per cent, aqueous 
solution of gallotannic acid has a specific gravity of 1003.8 
at 15.5 C. 

The extract or decoction of the substance is diluted to 
a litre, and its specific gravity determined at i5.5C. 
(e.g., 1003.86). It is then shaken with dry lead carbonate 
at intervals for two to three hours, after which it is filtered 
and the specific gravity of the filtrate determined. The 
loss in specific gravity (e.g., 1003.86 1001.52 = 2.34) 
divided by 3.8 and multiplied by 20 gives the percentage 
of tannin absorbed by the lead (e.g., in this case =12.30 
per cent.). 

Jackson obtained the following results with solutions 
of 5 per cent, strength : 






Specific 
gravity of 
solution. 


Specific 
gravity of 
filtrate. 


Tannin 
Per cent. 


Valonia .... 


1009.08 


1003.33 


30.2 


Sumach . . . . 


1008.25 


1003.61 


24.4 


,, . . . ' -' 


1009.61 


1005.08 


23.8 


Oak-wood extract 


1007.33 


1003.15 


21.9 


Chestnut wood extract 


1006.06 


1002.48 


18.8 



The filtrate from the lead precipitate in this method 
forms a black ink with iron salts, and the method is 
unsuitable for valuing tannin materials for ink manu- 

* Chem. News, 1884, 1. 1079. 






NATURE OF INKS 83 

facture unless used in conjunction with a colorimetric 
method. 

Ruoss's Ferric Sulphate Method.* This is based 
upon the formation of sodium tannate and the subsequent 
precipitation of the tannic acid as the compound 
C 14 H 9 O 9 (FeO) (vide supra) by means of a solution of 
ferric sulphate containing sodium tartrate to prevent 
spontaneous formation of basic ferric oxide and acetic 
acid to dissolve the ferric hydroxide, which would 
otherwise be precipitated simultaneously with the tannic 
acid. 

The reagents required are: (i) a solution of 50 grms. 
of ferric sulphate (or an equivalent quantity of ferric 
chloride or ferric ammonium sulphate) per litre ; (2) a 
semi-normal solution of crystalline sodium carbonate 
(71.3625 grms. per litre); and (3) a solution of 5 
grms. of sodium tartrate in a litre of dilute (6 per 
cent.) acetic acid. 

It is essential that the ferric sulphate be at least 
equivalent to the sodium carbonate solution, i.e., when 
10 c.c. of each are boiled together and filtered, the filtrate 
must not give an alkaline reaction with methyl orange. 
In preparing it the liquid must not be boiled, or basic iron 
compounds will be deposited. 

A further test to be applied to the solutions is that 
on mixing 50 c.c. of water, IO c.c. of solution (i) and 
10 c.c. of solution (2), and immediately adding 25 c.c. of 
solution (3), the liquid must remain perfectly clear after 
being boiled for five minutes. 

The tannin solution may be neutral or faintly acid 
or alkaline, but must not contain more than 0.4 per 
cent, of tannic acid. 

In the determination 50 c.c. of such a solution are 
shaken with 10 c.c. of solution (2) and 10 c.c. of reagent 
(i) (an evolution of carbon dioxide taking place), and then 
immediately mixed with 25 c.c. of the sodium tartrate 
solution (3), well shaken, and boiled for five minutes. It 
is then filtered, and the precipitate washed until the 
washings are free from iron, and then dried, ignited, and 
weighed. 

* Zeit. anal. CJiem.. 1902, xli. 717. 



84 INKS AND THEIE MANUFACTURE 

The weight of the residue multiplied by the factor 

3 21 - 22 -7 01 = 4.024 
56 

gives the amount of tannic acid (mol. weight = 32 1.22) in 
50 c.c. of the tannin solution. 

Gallic acid treated in the same way gives a brown colora- 
tion, but no precipitate with the reagents, and passes into 
the filtrate, where it might be determined colorimetrically. 

This method has not proved satisfactory in our hands as 
a means of determining the value of tannin material for 
the manufacture of ink ; and although closely following 
the directions given, we have been unable to obtain 
concordant results in experiments with solutions of pure 
gallotannic acid. 

Colorimetric Methods. It is obvious that the ordinary 
gravimetric methods used by the leather manufacturer 
for the valuation of tannic materials are not very suitable 
for the purposes of the ink manufacturer who wishes to 
take into account all the substances capable of forming 
coloured compounds with iron salts, and not merely those 
forming insoluble compounds with gelatin. 

The filtrate from the determination of tannin by 
Procters method almost invariably gives a dark colour 
with solutions of ferric salts, and this is more marked in 
the case of samples of old material in which the original 
gallic acid has undergone more or less decomposition. 
For instance, we found old English oak-apple galls to 
contain 1 1 per cent, of tannin by the gelatin absorption 
method, whereas the filtrate from the gelatin compound 
gave a deep blue-black colour with ferric salts, and when 
tested by our colorimetric method was found to contain 
substances equivalent in tinctorial effect to an additional 
1 8 to 19 percent, of gallotannic acid. 

Hinsdale's Colorimetric Method. Hinsdale * has 
described a method in which the reagent was prepared 
by dissolving 0.04 grm. of potassium ferricyanide in 
500 c.c. of water and adding 1.5 c.c. of ferric chloride 
solution (Amer. Pharm. strength). 

* Amer. Journ. Pharm., 1890, Ixii. 119. 






NATURE OF INKS 85 

The standard tannin solution consisted of 0.04 grm. of 
pure gallotannic acid dried at IOO C. 

In determining the proportion of tannin in, e.g., oak 
bark, 0.8 grm. of the sample was exhausted with suc- 
cessive quantities of boiling water, and the extract made 
up to 500 c.c. Five drops of this extract were then 
treated with 5 c.c. of the reagent, and the same quantity 
added to 4, 5, 6, 7, and 8 drops of the standard tannin 
solution. After one minute 20 c.c. of water were added, 
and the colours matched within three minutes. 

Hinsdale asserts that the method is applicable to any 
substance containing less than 10 per cent, of tannin. In 
the case of stronger solutions an equal volume of water 
must be added and the results multiplied by 2. 

We have made a number of determinations by this 
method, but in our opinion it has the drawbacks of 
requiring the tannin solution to be so very dilute, whilst 
the reagent, in addition to being unstable and possessing 
too dark a colour, gives somewhat indecisive colorations 
with tannin, which are not easy to match. 

We therefore discarded it in favour of the following 
colorimetric process. 

Mitchell's Colorimetric Method.* The reagent 
consists of a solution of o. I grm. of ferrous sul- 
phate and 0.5 grm. of sodium tartrate in 250 c.c. of 
water. On adding this to a dilute solution of gallotannic 
acid or gallic acid a violet coloration is produced, the 
intensity of which is proportional to the amount of these 
acids present. 

The standard solution for colorimetric comparison con- 
sists of O.I grm. of dried gallotannic acid in 500 c.c. of 
water, and the whole of the i substances giving a coloration 
with the reagent are expressed in terms of gallotannic 
acid. 

Gallic acid may also be used for the standard solution, 
and the results expressed in terms of that acid. 

The colori metrical comparison maj^ be suitably made in 
the tubes first designed by Hehner for Nesslerising water. 
These are placed on a white tile, and the colour of the 

* Unpublished. 



86 



INKS AND THEIR MANUFACTURE 



liquid in each matched. The amount of gallotannic acid 
in the tube containing the standard solution being known, 
the equivalent amount in the other tube can then be 
readily calculated. 




Fig. 28. Hehner's Nesslerising tubes. 

In this way the following results were obtained : 

Nut galls, 44 per cent. ; oak-apple galls, 30.7 per cent. ; 

divi-divi, 34 per cent. ; valonia, 57.5 and 59 per cent. ; 

myrobalans, 39 per cent. ; Japanese galls, 56 per cent. ; 

and Chinese galls, 62 per cent. 



CHAPTER IV. 

MANUFACTURE OF IRON GALL INK. 

CONTENTS. The relative proportion of galls and ferrous sul- 
phate Deductions from the composition of ink deposits Old 
type of iron gall ink Old formulas of iron gall inks 
TJnoxidised iron gall inks Gallic acid inks Japan 
inks. 

THE process of preparing ink from Chinese or Aleppo 
galls is a very simple one. The galls are crushed, mixed 
with straw, and treated with hot (not boiling) water in a 
high narrow oak vat containing a false bottom. The 
liquid percolates through small holes in this, its passage 
being assisted by the presence of the straw, and is then 
drawn off through a cock and pumped over the goods 
again and again until the whole of the tannin has been 
extracted. 

The final extract, which should contain from 5 to 6 per 
cent, of tannin ( Viedt), is then mixed with a solution con- 
taining the necessary amount of ferrous sulphate. 

THE RELATIVE PROPORTION OF GALLS AND FERROUS 
SULPHATE. 

Historical Opinions. If we compare the numerous 
formulae given by different chemists who have investi- 
gated the subject, it will be observed that there is fre- 
quently a great discrepancy of opinion. 

One of the earliest published formulas is that given in 
1660 by Canneparius,* in which 3 parts of galls are to be 
used to I part of ferrous sulphate. 

Lewis,* who made experiments with varying quantities 

* De Atramentis. f loo. cit. p. 377. 



88 INKS AND THEIR MANUFACTURE 

in 1748, found that equal parts of galls and ferrous sul- 
phate yielded a good black ink, but that the colour faded 
in a few days to brownish-yellow on exposing the writing 
to the light. An infusion from 2 parts of galls mixed 
with i part of ferrous sulphate had not faded so much 
after two months' exposure, whilst with a proportion of 
3 to I the colour was preserved still better. By still 
further increasing the proportion of galls to 6 : I, the 
writing was paler but more durable. The proportion of 
water was found to admit of much greater variation, but 
40 to 50 parts yielded an ink of sufficient blackness and 
permanency. 

Ribeaucourt * confirmed Lewis s statement as to the 
influence of an excess of iron upon the writing, and also 
showed that when the galls were in excess the characters 
soon changed to brownish-yellow on exposure. 

From his experiments he concluded that a proportion of 
2 of galls to I of ferrous sulphate was sufficient to make 
a good ink, and that Lewis's proportion of 3 to I was too 
great. 

Other proportions recommended are 4 : I (Eisler^ 
I 770)l 5 : i (Reid%); 1.5 : i (Erande); 2.4 : I (Ure\\)\ 
&c. &c. 

All these proportions were obtained, empirically, with 
galls which probably contained very variable proportions 
of gallotannic acid, and by methods in which different 
amounts of that substance were brought into solution. But 
making allowance for this, the balance of opinion, which 
is also supported by numerous authorities not quoted 
above (Booth, Karmarsch, ffochheimer, &c.), is in favour 
of a proportion of 3 parts or thereabouts of galls to i part 
of ferrous sulphate. 

This conclusion is supported by the experiments of 
SMuttig and Neumann on the composition of the insol- 
uble iron compound that forms on exposing the solution of 
gallotannic acid and ferrous sulphate to the action of the 
air, and by our own experiments on similar lines. 

* Ann. de Chim., 1792, xv. 113. 

f Loc. clt. J Phil. May., 1827, ii. 114. 

Diet, of Science, art. Ink. |j Diet, of Chew. 



MANUFACTURE OF IRON GALL INK 89 

Deductions from the Composition of Ink Deposits. 
Of the numerous compounds of tannin and iron, which 
have already been described (p. 76), that formed during 
the spontaneous oxidation of the ink is the only one that 
need be considered here, for the insoluble tannate pro- 
duced by oxidation with hydrogen peroxide has a com- 
pletely different composition (loc. cit., supra). 

Wittstein * exposed a solution of tannin and ferrous 
sulphate in the proportion of 3 : I to the atmosphere for 
a month and a half, and thus obtained an insoluble 
precipitate which, when dried at 100 C., yielded 8.40 per 
cent, of ferric oxide ( = 5.88 per cent, of iron). He 
proved that gallic acid was not formed in the oxidation, 
since the liquid, after repeated treatment with gelatin to 
remove tannic acid, yielded a filtrate which did not darken 
on the addition of ferric salts. The precipitate contained 
T V of its iron in the ferrous state. 

The formula which best corresponds with this proportion 
of iron is that suggested by Schiff,\ which requires 8.5 per 
cent, of iron : 

Fe (C 14 H 9 9 ) 5 
)>C 14 H 8 9 
' (C 14 H 9 9 ) 5 

Schluttig and Neumann.^ on repeating Wittsteirts 
experiments, obtained a series of five spontaneous pre- 
cipitates which they removed from the ink from time to 
time, the final one being collected after an exposure of 
five weeks. These five precipitates, dried at 1 00 C., were 
found to contain from 6.27 to 6.6 1 per cent, of iron, the 
average in the five being 6.35 per cent. 

Precipitates obtained in the same manner and allowed to 
dry spontaneously in the air contained on the average 
4.8 per cent, of iron. A complete analysis of one of these 
air-dried deposits gave the following results: Carbon, 
35.77; hydrogen, 5.19; iron, 4.80; and oxygen, 54.24 
per cent. When these precipitates were dried at 100 C., 
the dark violet colour changed to black, and they were 

* Jahresber. der Chem. (von Berzelius), 1848, xxviii. 221. 

f Ann. Client. Pharm., 1875, clxxv. 176. 

I Die Eisengallvstlnten, Dresden, 1890, p. 44. 



90 INKS AND THEIR MANUFACTURE 

Amount of Iron in Spontaneous Deposits from Inks. 







s 




Time 


o -~ *- 


- 


No. 


Tamiin, &c. 


O 3 
Si! 


3 


before col- 
lecting the 


'E~ g 

^ "2 $ 


if 






* 55 


* 


deposit. 


* 








Grms. 


C.c. 




/0 


/0 


I 


Gallotannic acid (86 %) (2 grms.) 


3 


100 


i month 


822 


5-75 


2 





>5 





3 days. 


849 


5-94 


x 


Gallotaunic acid (86 %) (3 grins.) 


3 


IOO 


i week. 


7.85 


549 


2 





" 


" 


" 


8.63 


6.04 


I 


Gallic acid (3 grms.) (very slight 


2 


250 


2 mouths 


25 


I7-.S 




deposit) 












I 


Chinese galls, decoction from 12 


3 


200 


10 days 


98 


6.8 




grms. 












2 


>> 11 


v 





7 11 


10.3 


7-2 


3 


V 11 11 


,. 





3 weeks 


10.8 


7-55 


4 


11 


" 


" '-' 


2 


10.81 


7-56 


I 


Aleppo blue galls, decoction from 5 


i 


2OO 


4 days 


8.62 


6.04 




grms. 












2 


11 11 11 11 


,, 


,, 


TO 


11.03 


7-72 


3 


11 


" 


" 


3 weeks 


10.6 


7-4 


I 


English oak-apple galls, from 5 


i 


200 


2 weeks 


14.8 


10.3. 




grms. 












2 


., 








i week 


129 


9.0 


3 


" 


" 


" 


i 


13-1 


9.2 


I 


Japanese galls (5 grms.) 


i 


3CO 


6 days 


11.31 


7-9i 


2 


11 11 11 








3 weeks 


ii 02 


7.71 


3 











6 days 


n.6 


8.12 


I 


Divi-divi (5 grms.) 


i 


200 


2 weeks 


9.70 


6.77 


2 


Ink decanted from first sediment 


" 


" 


2 


ii. ii 


7-77 


I 


Yalonia (5 grms.) 


i 


200 


i week 11.53 


8.! 


2 


11 11 . 


" 


'' 


2 weeks 12 78 


8.9 


I 


Myrobalans (5 grms.) 


i 


2OO 


2 weeks 8.21 


5-74 


I 


Chestnut extract (5 grms.) 


5 


200 


i month 


!0.53 


7-37 






MANUFACTURE OF IRON GALL INK 91 

then found to contain 6.34 per cent, of iron, or the same 
proportion as the deposits dried directly at that tempera- 
ture. 

The ratio of iron to tannin was thus as I : 14.27 (or I 
part of ferrous sulphate to 2.88 parts of tannin) a result 
which agreed fairly well with Dieterictis empirical propor- 
tion of i part of iron to 1 5 parts of tannin. 

As there was considerable discrepancy between the 
composition of the deposits obtained by Wittstein and by 
Schluttig and Neumann we thought it advisable to once 
more repeat the work, using not only tannin, but also 
extracts of different kinds of galls. 

Our results, which, as will be seen, were obtained under 
very varying conditions, are summarised in the preceding 
table. 

Our results with pure gallotannic acid are thus more 
in agreement with those of Wittstein than with those of 
SchhUtig and Neumann. 

It was hardly to be expected that galls should not 
contain other substances besides gallotannic acid forming 
insoluble compounds with iron, and this probably accounts 
for the higher percentage of iron found in the deposits 
from English oak-apple gall ink, &c. 

We found that the precipitates attacked the paper if 
dried on the filter at 100 C., and we therefore in most 
of our experiments washed the deposits into a platinum 
basin, in which they were subsequently dried and ignited. 

The ratio between the iron and gallotannic acid in our 
dried deposits was as I : 16, which corresponds with a 
ratio of i : 3.22 between the ferrous sulphate and gallo- 
tannic acid. 

Hence each part of ferrous sulphate requires 3 parts 
of pure gallotannic acid. Since, however, the proportion 
of tannic acid varies in each kind of material employed, 
the proportion of tannin material must naturally vary 
correspondingly. 

The following table, giving the approximate proportions 
of different materials, is based upon the average amount 
of tannin they contain, and on the results of the preceding 
experiments. It is assumed that practically the whole of 
the tannin is extracted in each case. 



92 



INKS AND THEIR MANUFACTURE 



Proportion of Tannin Materials required ly 1 part of 
Ferrous Sulphate. 



Tannin material. 


Containing 
pure taunic 
acid. 


I 
Parts by 
weight 
required. 




Per cent. 






(circa). 




Commercial gallotannic acid 


86 


3-8 


Aleppo galls ... 


62 


5-o 


Chinese galls 


75 


4-3 


Japanese galls 


62 


5-o 


Acorn galls (Knoppern) 


3 


ii 


English oak-apple galls 


26 


12.5 


Chestnut wood . . .. . .> 


9 


36 


extract . . 


20 


16 


Sumach . ... . 


22 


14.6 


Valonia* .*.''. ... 


30 


ii 


Divi-divi . . . *. ' < 


40 


8 


Myrobalans ... ... 


30 


ii 



OLD TYPE OF IRON GALL INK. 



When solutions of gallotannic acid and ferrous sulphate 
are mixed the liquid at first remains colourless, and it is 
only when oxidation takes place that a violet-black solution 
and eventually a violet-black deposit is formed. 

In the older type of iron gall inks it was therefore 
necessary to expose the liquid to the air for some time to 
obtain an ink which would give writing of sufficient im- 
mediate blackness, although even the writing with the 
colourless solution of gallotannic acid and ferrous sulphate 
gradually becomes black when dried. In other words, a 
"provisional colour" was formed by partial oxidation of 
the ink, and the insoluble deposit was kept in suspension 
by the addition of a sufficient quantity of gum arabic. 

Ink thus oxidised yielded an immediate black writing, 
but had the drawback that that portion of the ink in which 
the oxidation was complete did not penetrate into the 
fibres of the paper, but was attached to the surface by 
means of the gum and could be washed off. 

* See also colorimetric results on p. 86. 









MANUFACTURE OF IRON GALL INK 93 

In a good iron gall ink of the old type it was therefore 
essential to have only so much of the ink oxidised as to 
give an immediate black colour, leaving the remainder 
in an unoxidised state to penetrate into the paper, and 
form the black insoluble oxidised tannate within the 
fibres. 

On boiling an iron gall ink the oxidation process is 
accelerated, and there is also some decomposition of the 
tannate, so that a complete ink should not be boiled. 

Provisional Colouring Matters. The paleness of the 
writing with unoxidised ink has also been obviated in 
many inks by the addition of logwood extract (p. 102), or 
more recently of various aniline colours (p. 13). Such 
colouring matters as Prussian or Turnbull's blue, ultra- 
marine, or the various blue compounds of .copper, are quite 
unsuitable for the purpose, since they are either too insol- 
uble or react with the tannin and injure the colour of iron 
tannate. The most suitable and most widely employed 
substance as a provisional colour is indigo, the presence of 
which is a characteristic feature of the so-called " aliza- 
rine " inks (vide infra). 

Old Formulae of Iron Gall Inks. The earliest method 
of preparing iron gall ink that we have discovered is that 
of the Elizabethan domestic ink, the formula of which is 
shown in the frontispiece. 

Elizabethan Ink. Rain water (or claret wine or red 
vinegar), i quart ; galls, 5 oz. ; ferrous sulphate, 4 oz. ; 
gum, 3 oz. After five days' soaking, the extract from the 
galls was heated just to the boiling-point with the ferrous 
sulphate (see also the rhyme of de Beau Chesne, p. 12).! 

Canneparius* (1660). Galls, 3 oz., macerated in 30 oz. 
of white wine for aix days, and the extract mixed with i oz. 
of ferrous sulphate and 2 oz. of gum arabic, and left for 
four days. 

Lewis 1[ (1760). Galls, 3 oz. ; rasped logwood, i oz. ; 
water, 2 to 3 parts ; gum, varied at discretion, but about 
J oz. per pint. The ink to be shaken daily for ten to twelve 
days. 

" Celebrated Black Dresden Ink " ( 1 770). J - Galls, 2 Ibs. ; 
ferrous sulphate, J Ib. ; gum, 6 oz. ; alum, 2 oz. ; verdi- 
* De Atram-entis, p. 270. f loc. clt. p. 377. 



94 INKS AND THEIR MANUFACTURE 

gris, I oz. ; and salt, I oz. ; in 2 quarts of vinegar and 2 
quarts of rain water. Decanted after two days and shaken 
daily for eight days. 

Eisler* (1770). Galls, 4 oz. ; ferrous sulphate, 2 oz. ; 
gum, I oz. ; in a quart of rain water. 

Ribeaucourt f (1792). Galls, 2 oz. ; ferrous sulphate, 
I oz. ; copper sulphate, J oz. ; gum, I oz. ; and logwood, 
I oz. ; in 24 oz. of water. 

Reid I (1827). Galls (i Ib.) extracted twice with 3 pints 
of boiling water, and the extract (2 quarts) mixed with 
3^ oz. of ferrous sulphate and the same quantity of gum. 

UNOXIDISED IRON GALL INKS. 

The use of indigo as a means of improving the colour of 
ink was mentioned by JSisler in 1770 (loc. cit.\ and was 
used in this country by Stephens^ in 1836. 

In 1856 Leonhardi,\\ of Dresden, patented in Hanover 
an ink consisting of an extract of 42 parts of Aleppo 
galls and 3 parts of madder in 120 parts of water, mixed 
with ii parts of indigo solution, 5-!- parts of ferrous 
sulphate, and 2 parts of metallic iron, dissolved in crude 
acetic acid. Subsequently the madder was omitted as 
superfluous, but the inks still retained the name of 
"alizarine" ink, although quite free from alizarine. The 
more suitable name of " isatin " inks never met with 
popular acceptance. 

In " alizarine " inks the process of oxidation is pre- 
vented as far as possible, thus keeping the liquid free, to 
a large extent, from insoluble deposit, and giving it much 
greater power of penetration into the paper. The pre- 
sence of the indigo makes the writing immediately blue, 
and it subsequently changes to black as the oxidation of 
the iron tannate proceeds within the fibres of the paper, 
the oxidation process being completed in eight days at 
the most. 

The addition of indigo also increases the permanency of 
the ink, so that the writing offers much more resistance 

* Eisler, Dintefass, p. 7. f Ann. de Chim., 1792, xv. 113. 

J Philos. Mag., 1827, ii. 114. Mechanics' Mag., 1836, xxv. 229. 
|| Dingier' s polyt. Journ., 1856, cxlii. 141. 






MANUFACTUKE OF IRON GALL INK 95 

to the action of bleaching agents than ordinary iron gall 
inks. 

Owing to the absence of gum the inks flow more readily 
from the pen, and are less liable to clog ; but, on the 
other hand, the presence of free acid in considerable pro- 
portion causes the pen to be corroded. 

Thus we found that an ordinary steel pen left in a 
typical commercial "alizarine" ink from which air was 
excluded had lost 5 per cent, in weight after six weeks, 
whilst the ink itself had become semi-solid. 

Indigo blue is soluble in concentrated sulphuric acid, 
and the solution can be diluted to a great extent without 
yielding a deposit. 

Viedt* gives the following method of preparing " aliza- 
rine " ink : a 5 to 6 per cent, solution of sulphindigotic 
acid is treated with sufficient iron to form the necessary 
amount of ferrous sulphate for the tannin present. The 
excess of free acid is then nearly neutralised with chalk 
or marble, leaving only a slight amount to retard atmo- 
spheric oxidation of the ink. The clear solution is then 
decanted from the insoluble calcium sulphate and mixed 
with a 5 to 6 per cent, decoction of galls, yielding a green 
solution through the mixture of the yellow gall extract 
and blue indigo solution. 

Inks containing neutral indigo carmine, i.e., the sodium 
or potassium salt of sulphindigotic acid, yield deposits 
much more readily than inks containing free sulphuric 
acid, though the latter also form sediments in time. 

Indigo carmine is prepared by dissolving indigo in 
sulphuric acid, adding alkali, and collecting and washing 
the precipitate. 

Prollius' " Alizarine " Ink, which was recommended by 
Bley\ as superior to any then sold, was prepared from (i) 
i\ Ibs. of galls, with sufficient water to yield 5 Ibs. of 
decoction; (2) 4 oz. of indigo powder mixed with ij Ibs. 
of fuming sulphuric acid, and allowed to stand for 24 
hours ; then diluted with 5 Ibs. of water, treated with 8 oz. 
of powdered chalk, and 8 oz. of iron filings, filtered and 
added to (i). 

* Dingier'*? polyt. Jo-urn., 1875, ccxvi. 533. 
f Ibid. 1857, cxlv. 77. 



96 INKS AND THEIR MANUFACTURE 

With the object of reducing the corrosive action of the 
sulphuric acid in the ferrous sulphate upon steel pens 
several manufacturers have proposed to ignite ferrous 
sulphate until a white powder was left. It is difficult to 
see what advantage such a process can have. 

Desormaix's gall ink* and Heinle 's non-corrosive wi&t 
were prepared in a similar manner. 

GALLIC ACID INKS. 

Edcl,\ in the course of his investigation on gall inks, 
pointed out that after the conversion of gallotannic acid 
into gallic acid more than twice as much ink was produced. 
Thus 448 parts of galls required 144 parts of ferrous sul- 
phate, but after the conversion of the gallotannic acid into 
gallic acid 336 parts of the iron salt were necessary to 
obtain an ink of the same intensity. 

To effect this conversion in practice, he exposed a decoc- 
tion of lib. of galls to the air for ten days with continual 
daily shaking, and then added to each quart of the liquid 
3^ pints of water, 9 oz. of ferrous sulphate, and 9 oz. of 
gum. 

Dieterich has also recommended inks prepared from 
gallic acid solutions obtained by the oxidation of gall 
extracts or tannin solutions. 

Oxidised Gall Extracts. 200 parts of powdered Chinese 
galls are moistened with water and kept in a warm place (20 
25 C.) until quite mouldy, the water being renewed daily, 
so that the galls feel moist but not wet. After eight to ten 
days the fermentation is complete, and the galls are ex- 
tracted with successive portions of hot water, and filtered 
after the addition of some talc, the total amount of extract 
and washings amounting to IOOO parts. 

Oxidised Tannin Solutions. 100 parts of tannin, 100 
parts of water, and 20 parts of hydrochloric acid (sp. gr. 
1.16) are heated for ten hours on the water bath at 80 
90 C., and then gradually diluted with 900 parts of dis- 
tilled water. 

* Nicholson's Diet, of Chein., 1820, p. 507. 

f Prechtl's Technol. Encyclop., 1852, p. 460. 

| P/nlosojrft. Mag., 1827, ii. in. 

Pharm. Manual, 1897, p. 680. 



MANUFACTURE OF IRON GALL INKS 97 

For writing inks Dieterich finds that either ferrous or 
ferric salts can be used with such oxidised solutions, but 
for copying inks only ferrous salts can be employed (see 
chap. xii.). He gives the following directions for preparing 
inks on these lines : 

I. Gall Ink. 1000 parts of the oxidised gall decoction 
are mixed with 100 of ferric chloride solution containing 
10 per cent, of iron, the ink left for two weeks in closed 
flasks and then decanted. 

II. Oxidised Tannin Office Ink. 100 parts of tannin, 
100 of water, 200 of ferric chloride solution (10 percent. 
of iron), and 10 per cent, of crude hydrochloric acid (sp. gr. 
1. 1 6) are mixed and heated for ten hours at 8o 90 C. 
The liquid is then diluted with 700 parts of hot water, left 
for an hour at the same temperature (with renewal of the 
evaporated water), cooled, kept in a closed flask for two 
weeks, filtered, and diluted to 1000 parts. 

With inks thus prepared the writing is at first hardly 
perceptible, so that a provisional colour is necessary, as in 
the case of the following formulas : 

Blue-black Iron Gall Ink. Three parts of phenol blue in 
400 parts of water are mixed with 600 parts of oxidised 
gall ink (I.) and I part of phenol, and left for a week in a 
loosely covered flask, after which the clear ink is decanted. 

Violet-black Ink. Prepared in the same way, except 
that 1.5 parts of phenol blue 3 F., and 2.0 parts of Ponceau 
red R.R. are used, instead of the 3 parts of phenol blue as 
the provisional colour. 

Bed-black Ink. Six parts of Ponceau red R. used. 

Green-black Ink. Six parts of aniline green used. 

Black Ink. The provisional colour consists of 10.5 parts 
of aniline green D, 9 parts of Ponceau red R, and I part 
of phenol blue 3 F. 

" Alizarine J| Ink. Four parts of indigotin, and 2.4 parts 
of aniline green as colouring matter. 

Blue-green Ink. 1.5 parts of phenol blue, and 2.5 parts 
of aniline green as colouring matter. 

For the formulae of gallic acid copying inks on these 
lines see chap. xii. 

State of Massachusetts Official Ink. This is a mixed 
tannic and gallic acid ink, containing the following con- 



98 INKS AND THEIR MANUFACTURE 

stituents : Dry gallotannic acid, 23.4 ; gallic acid crystals, 
7.7 ; ferrous sulphate, 30; gum arabic, 25 ; dilute hydro- 
chloric acid, 25 ; and phenol, i, in looo parts of water. 

JAPAN INKS. 

When an iron gall ink has been oxidised so as to have 
become converted for the most part into the insoluble black 
iron tannate (p. 13), it no longer possesses the penetrating 
properties of the freshly prepared ink, and requires the 
addition of a considerable amount of gum to keep the in- 
soluble powder in suspension. 

Such ink gives an immediate black writing, which dries 
on the surface of the paper with a varnish-like gloss, whence 
this sort of ink was termed Japan ink by Ribeaucourt. 

Since the oxidation has taken place within the ink 
instead of partially within the fibres, as in the old type of 
partially oxidised gall inks, Japan inks are more easily re- 
moved than other gall inks. They have also the drawback 
of stickiness and of the excess of gum clogging the pen, 
whilst they also readily yield large deposits. 

Ribeaucourtfs Japan Ink contained the ingredients given 
in the formula on p. 94. In Neiuton's English patent 
(No. 836; 1865), complete iron gall ink was oxidised by 
being percolated through narrow openings in the bottom of 
a vessel; whilst Carter (Eng. Pat., No. 1982; 1873) obtained 
the same results by subjecting the ink to the action of a 
current of air. 

Both of these processes produce "Japan" inks of the 
very opposite type to " alizarine " inks. 



CHAPTER V. 

LOGWOOD, VANADIUM AND ANILINE BLACK INKS. 

CONTENTS. Logwood inks Logwood Logwood extract 
Haematoxylin Hsematein Iso-hfematein Addition of log- 
wood to gall inks Logwood inks without tannin Chrome 
logwood inks Hasmatein inks Use of logwood in patent inks 
Vanadium inks Black aniline inks. 

LOGWOOD INKS. 

Logwood. This well-known dyeing material consists of 
chips of the wood of Hcematoxylon Campechianum, a large 
tree (40 to 50 feet high) belonging to the Ocesalpiniacece. 
It forms large woods on the Atlantic side of Central America, 
in Mexico, and in the West Indies. 

It was first discovered by the Spaniards in the Bay of 
Campeachy, in Mexico, and exported by them into Europe.. 
When introduced into England in the reign of Queen 
Elizabeth, it was soon employed to adulterate other dyes,, 
and its use was prohibited as " affording a false and deceitful 
colour" injurious to the Queen's subjects, "and discreditable 
beyond seas to our merchants and dyers." This Act was 
not repealed until 1661. 

The constant hostilities between the Spanish and 
English led to the tree being acclimatised in the W'est 
Indies in 171 5, though subsequently a treaty was concluded 
giving the English the right of cutting and exporting the 
wood from Campeachy. 

The best Indian logwood is not so valuable as the 
Mexican product, whilst Honduras wood is intermediate in 
value. 

In preparing it for the market, the wood is first divided 
into logs about 3 feet in length, which are then cut into- 



100 INKS AND THEIR MANUFACTURE 

chips by means of a revolving drum provided with steel 
catting knives. 

Logwood Extract. Formerly the chips were moistened 
and exposed to a fermentation process, but manufacturers 
now endeavour to exclude all oxidising influences. 

Three methods are in use in the preparation of the log- 
wood extracts of commerce.* The finely divided chips are 
frequently digested with hot water under a pressure of I 
to 2 atmospheres, this process yielding a large extract, 
which, however, contains a considerable proportion of 
resins, fats, and other impurities ; (2) the French method 
of boiling the chips with water at the ordinary pressure, 
which yields a smaller though purer extract; and (3) a 
diffusion process, in which an apparatus similar to that 
used in the sugar industry is employed. The yield by this 
process is smaller than in (i) or (2), but the shades of colour 
are finer. 

If the wood has not undergone any fermentation, the 
extracts contain chiefly haematoxylin and but little haema- 
tein. They are sold either as liquids, with a density of 
about 10 Be., or as solid gum-like masses. 

The tinctorial value of an extract is usually determined 
by practical dyeing tests, the amount of colour fixed on 
wool mordanted with potassium bichromate and tartaric 
acid on treatment with a definite quantity of the dried 
sample, being compared with that given by a sample of 
standard quality. 

Logwood extract may be adulterated with molasses or 
tannin materials, though according to Rupe (loc. cit.) adul- 
teration is not so frequent now as formerly. 

Hsematoxylin [C 16 H 14 6 ]. The colouring matter of 
logwood does not occur ready formed in the cells, but in the 
form of a compound, hcematoxylin, which becomes purple 
on oxidation. 

Heematoxylin was first discovered by Ckevreul f in 1810, 
and termed hcematin by him, a name subsequently changed 
to hcemato&ylin by Erdmann, t in order to prevent con- 
fusion with the colouring matter of blood. 

* Rupe, Die Chem. der natur. Farbstoffe, p. 107. 
f Ann. Ckim. Phys., 1812, Ixxxii. 53, 126. 
j Ann. diem. Pharin., 1842, xliv. 292. 



LOGWOOD, &c., BL J AdK IKKS 101 

It was obtained by Hesse * in the form of colourless 
crystals containing 3 molecules of water [which they lost 
at I2OC.], by extraction with ether containing some 
water and in the presence of alkali bisulphate. 

Properties. Hasmatoxylin has a sweet taste and is 
slightly soluble in water, but dissolves readily in alcohol 
and ether. The crystals turn red on exposure to the light 
(in the absence of air) without changing in composition. 

Solutions of silver and gold salts are rapidly reduced by 
them, as is also the case with Fehliug's solution. Stannous 
chloride gives a rose-coloured precipitate, ferrous ammo- 
nium sulphate a slight violet black precipitate, and lead 
acetate a white precipitate changing to blue. 

On dry distillation hsematoxylin yields pyrogallol and 
resorcinol (or a derivative). 

From a consideration of the results obtained on acetyla- 
tion Reim"\ concluded that hgematoxylin had the constitu- 
tional formula 

C 6 H 2 (OH) 3 

C 6 H 4 



Haematein (C 10 H 12 6 ). The colouring principle of log- 
wood, which is first formed by the oxidation of the pre- 
existing hgematoxylin, was discovered by 0. Erdmann (loc. 
<.)-C w H M 6 + = C 16 H 12 6 + H 2 . 

It forms small anhydrous yellowish-green crystals with 
a metallic lustre. These are only slightly soluble in 
water, alcohol or ether, though the solution in water 
(0.06 per cent, at 20 C.) has an intense colour. 

It is readily soluble in alkalies yielding violet or 
purplish brown compounds. The ammonium compound, 
C 16 H 12 6 .2NH 3 is precipitated by most metallic salts. 
Thus it yields a violet blue precipitate with copper 
sulphate, a dark violet with alum, and a black one with 
iron ammonium sulphate, whilst it reduces a solution of 
silver nitrate (Hesse). I 

* Ann. Ckem. Pharm., 1859, cix. 332. 
f Ber. fl. d. diem. GfS., iv. 329. 
loc. clt 



102 ' INKS AND THEIR MANUFACTURE 

Hgematein is reduced to hasmatoxylin by treatment with 
sulphur dioxide or hydrogen. 

Iso-hsematein. When haematein is treated with 
concentrated sulphuric acid, it dissolves, forming a 
brown solution, from which, on standing, a crystalline 

P TT O ^ 
compound, 16 n rj 5 h S0 4 , is deposited (Hummel and 

Perkiri). * 

If hydrochloric acid be heated with hsematein in a 
sealed tube the colour of the solution changes to dirty 
yellow, and on evaporating the liquid a crystalline de- 
posit of iso-haematein hydrochloride is left. By treating 
this with silver hydroxide, and concentrating the solu- 
tion in vacuo, iso-hcematein is left as an amorphous mass 
with a greenish metallic lustre. 

Jso-hasmatein has the same composition as hasmatein, 
which ifc also resembles in its general reactions, though 
many of the metallic compounds have a more reddish 
shade of purple. 

Addition of Logwood to Gall Inks. The advantage 
of adding a small proportion of logwood decoction or 
extracb to iron gall inks has long been known. In 1763 
Lewis t made a series of experiments to determine 
whether such an addition had any injurious effect upon 
the stability of the ink, and found that the colour of the ink 
was materially improved without lessening its permanency. 

He recommended an ink consisting of 3 parts of 
galls, I of ferrous sulphate, and I of logwood in 40 
to 60 parts of water, with gum arabic in the proportion 
of J part to 20 of ink. 

Eisler's Logwood Gall Ink \ was prepared from the fol- 
lowing ingredients : Logwood, 8 oz. ; ferrous sulphate, 
S oz. ; vinegar, i quart ; rain water, J quart ; galls, 4 oz, ; 
gum arabic, 4 oz. ; alum, 2 oz. ; and indigo, I oz. The 
ink was left for fourteen days in the sun before using. 

Ribeaucourt in 1792 agreed with Lewis's statement as 
to the advantage of logwood in iron gall ink, and recom- 

* Ber. d. d. chem. Ges., xv. 2337. 

f loc. clt. p. 377. 

| Dintefasx, 1770, p. 8. 

Ann. de C/iiui., 1792, xv. 113. 



LOGWOOD, &c., BLACK INKS 103 

mended that its proportion should be half that of the 
galls. 

These earlier results have been fully confirmed in our 
time by the experiments of ScTiluttig and Neumann^* who 
found that ink prepared from hasmatoxylin and iron was 
even more permanent than those prepared from gallo- 
tannic or gallic acids. 

Reid's Gallic Acid Logwood Ink. Eeid-\ found that 
when gallic acid was employed in place of gallotannic acid 
logwood might be added in the proportion of I J parts to 
i part of the former. 

He prepared an ink 011 these lines by exposing a decoc- 
tion of galls (i lb.), to the air for ten days with occasional 
daily agitation, so as to convert the gallotanuic acid into 
gallic acid, and then adding a decoction of logwood ( i J Ibs.), 
1 8 oz. of ferrous sulphate, and 18 oz. of gum. 

This ink is decomposed by alkalies and alkali carbon- 
ates, the iron being precipitated. 

Logwood Inks without Tannin. Since haematoxylin, 
the active agent in logwood, contains three adjacent 
hydroxyl groups it follows the general rule established by 
Schluttiy and Neumann of yielding an ink with iron 
salts. 

The iron logwood inks have a greenish shade, which 
gradually changes to black as the writing dries, Alum 
logwood inks have a deep violet-black colour, and 
chromium logwood inks a violet colour changing to 
black, Chromic acid added to logwood gives a deep 
black precipitate, whilst potassium chromate yields a black 
ink, and if added in excess a black precipitate. 

In fact, as Viedt J has shown, precipitates are gradually 
formed by oxidation in logwood inks containing alum or 
iron or copper salts, though more slowly than in iron 
tannin ink. The addition of logwood in excess does not 
prevent this, but the deposition is retarded for a long time 
by completely excluding the air. 

Reiniges Iron Logwood Ink. This may be taken as a 

* Die Eisengallustuiti'n, p. 33. 

f Ph'dos. Jfag., 1827, ii. 115. 

j DlnyleSs polyt. Journ., 1875, ccxvi. 456. 

Ibid. 1857, cxliii. 240. 



104 INKS AND THEIR MANUFACTURE 

typical ink of this class. It is prepared by dissolving 
2 grms. of logwood extract, and 3 grms. of ferrous 
sulphate, in 100 c.c. of water, then adding 10 grms. of 
crystalline sodium carbonate, and finally, 2 grms. of 
oxalic acid. After complete settlement the ink is decanted 
from the sediment, and a suitable proportion of gum 
added. 

This ink gives a good black writing, but we have found 
that the characters become somewhat brown after two or 
three months. 

The writing gives a red coloration with hydrochloric 
and other acids, due to the logwood, and a bluish-green 
with acidified potassium ferrocyanide solution indicating 
the iron. It is gradually bleached by bromine water. 

Reid* who investigated the character of the inks 
formed on adding ferrous sulphate to logwood, found 
that the greenish-blue compound first formed was 
gradually oxidised to a brownish-black compound. 
Copious deposits were given, hdwever, by such logwood 
iron inks, and hence Reid concluded that logwood should 
not be employed alone, or should not exceed a third of the 
amount of the galls in mixed inks. 

Bb'ttgers Alum Copper Logwood lnk.-\ This is pre- 
pared by boiling i part of alum, 2 of copper sulphate, and 
4 of logwood extract with 48 parts of water, and filtering 
the solution. The filtrate is a red-violet ink, which writes 
pale violet, but rapidly darkens and soon becomes jet 
black. 

On treatment with bromine water the writing is 
changed to red, and then to faint brownish yellow. 

The great drawback of the ink is its instability, and 
it must be kept in tightly corked bottles, which should 
contain as little air as possible. Ink prepared by us and 
kept in a corked bottle containing air had yielded a dense 
deposit in six weeks, and gave only faint writing. 

Violet-Black Rouen Ink (Encre Ueu rouennaise).+ This 
consists of a decoction of 75 parts of logwood in 600 
parts of water, to which is added 3 J parts of alum, 3 parts 

* Philos. Mag., 1827, ii. 114. 

f Dingier''* polyt. Juttm., 1857, cxliii. 240. 

I Ibid, 1859, cliii. 77. 



LOGWOOD, &c., BLACK INKS 105 

of gum arable, and I J parts of sugar candy. The ink is 
allowed to stand for two or three days and then strained. 

Inks containing only logwood and alum write with a 
reddish-violet colour, which gradually changes to a dark, 
though not absolutely black, shade. 

Viedt's Copper Logwood Ink. * In Viedfs opinion 
copper sulphate should always be used in preference to 
ferrous sulphate in logwood ink, since it gives a blacker 
writing. 

He recommends the following formula: Logwood 
extract, 20 kilos, in 200 kilos, of water, mixed with a 
solution of IO kilos, of ammonium alum in 20 kilos, of 
boiling water, and the mixture treated with 0.2 of sul- 
phuric acid and 1.5 of copper sulphate in 20 litres of 
water. 

In order to obtain a darker liquid the ink is exposed to 
the air for some days before being bottled, thus producing 
a " provisional colouring," similar to that given by indigo 
in " alizarine " inks. Inks' of this type are sold under 
different names, e.g., Chemnitz violet-black ink. 

To obviate the paleness of the writing given by such 
inks as this Stark has prepared a writing and copying ink 
which gives immediate black characters by adding a little 
chromate to a copper logwood ink, the chrome ink in this 
case representing the "provisional colouring" matter (cf. 

P- 13)- 

Viedt (loc. cit.) states that he has never known an ink 
of this kind to gelatinise. 

A great objection to all logwood copper inks is that 
they cannot be used with steel pens, which gradually 
withdraws the copper from them. 

The addition of free sulphuric acid, as in Viedt's copper 
logwood ink (supra), retards the formation of a deposit, 
but causes the ink to corrode steel pens. 

Chrome Logwood Iiiks. Runge^ discovered that by 
adding a very small proportion of potassium chromate to 
a decoction of logwood a deep black fluid was obtained, 
which could be used at once as a writing ink, though by 

* Dingier' 1 s polyt. Journ., 1875, ccxvii. 76. 

f Gnmdrlss dcr Chem., 1847, ii. 205 ; Dingier'' 8 polyt. Journ., 184$, 
cix. 225. 



106 INKS AND THEIR MANUFACTURE 

increasing the amount of chromate a black precipitate was 
produced. 

Runge's Chrome Ink. This was originally prepared by 
boiling 10 Ibs. of logwood with water until 80 Ibs. of 
decoction were obtained, and adding potassium chromate 
in the proportion of I part in 1000. 

If solid extract of logwood be used, 1 5 parts are dis- 
solved in 1000 parts of water, and I part of potassium 
chromate added. 

Runge claimed for this ink the advantage of yielding 
permanent black writing, and of not acting upon steel 
pens. 

Gopel* considered that Runge's formula had too large a 
proportion of logwood, as shown by the red-brown edges 
of drops of the ink on white blotting paper, and advocated 
the following proportions : logwood extract 24, potassium 
chromate 2, and water IOOO parts. 

In the proportion recommended by Karmarsch (i of 
chromate to 8 of logwood extract), the ink is too grey, 
pointing to an excess of the chromate. 

Although Eunge had been able to use his ink con- 
tinuously for two years, it has been found by others that 
after a time a coagulation due to some unknown cause may 
occur. 

Stein f made numerous experiments to find a remedy for 
this, and eventually found that the addition of 4 grains of 
mercuric chloride to a bottle liquefied the coagulated ink 
and prevented it from becoming thick again. 

Viedt. however, asserts that Stein's remedy is useless, 
and that a better remedy is the addition of sodium car- 
bonate, as in Bottgers writing and copying ink (infra). 
He found that such ink, when kept in a well-closed ink- 
stand, remained fluid for two years, and hence concluded 
that the best means of preserving the ink was to com- 
pletely exclude the air. 

Bottger's Modification of Runge's Ink. Fifteen parts 
of logwood extract are dissolved in 900 parts of boiling 

* Dingier'* polyt. Jouni., 1859, cli. 80. 

f Ibid. 1850, cxv. 77. 

j Ibid. 1875, ccvii. 76. 

Ibid. 1859, cli. 431 ; 1869, csci. 175. 



LOGWOOD, &c., BLACK INKS 107 

water, and 4 parts of crystalline sodium carbonate dissolved 
in the clear decanted solution ; a solution of I part of 
potassium chromate in 100 parts of water is finally 
added. 

We have prepared ink by each of the above methods. 
Runges original formula gives an ink which yields very 
black characters, but requires the pen to be frequently 
filled, or the writing appears faint. The ink kept in a 
test-tube closed with cotton wool was perfectly liquid 
after three months, though it then yielded writing with 
a browner tinge. 

A simultaneous experiment in which a drop of formalin 
had been added to the ink gave analogous results. 

Ink prepared at the same time by Bottgers modification, 
and kept in a large well-closed flask (containing air), had 
a slight mould on the surface and gave dirty brown 
writing. Hence the addition of phenol or other preserva- 
tive is essential for this ink. 

According to Viedt, Plasters " Chrome Ink Powder' 1 and 
Poncelet's " Ink loithout Acid" are imitations of Eunge's 
original chrome ink. 

A " blue black ink," consisting of logwood decoction 
and chrome alum, gives writing which is too pale and 
grey. 

Bichromate Logwood Ink.* One hundred parts of log- 
wood extract are dissolved in 800 parts of lirne water, and 
when solution is complete, 3 parts of phenol and 25 parts 
of hydrochloric acid are introduced, and the whole left 
for thirty minutes on the hot-water bath. It is then 
cooled and filtered, 30 parts of gum arabic, and 3 parts of 
potassium chromate added, and the ink diluted to make 
1800 parts. 

This ink is violet-red in colour, and the writing at first 
appears reddish-brown, but rapidly darkens, and within 
five minutes has a bluish-black tint. It keeps well and 
yields very little deposit, but, owing to the amount of free 
hydrochloric acid present, it has a considerable action 
upon steel pens. Thus in one of our experiments a pen 
left in the ink had lost 4.5 per cent, in weight after six 
weeks, whilst the ink itself had become semi-solid. 
* Dingier'* potyt, Journ., 1882, ccxlv. 475. 



108 INKS AND THEIR MANUFACTURE 

The basic chloride and acetate of chromium are some- 
times used instead of potassium chromate in chrome inks 
in order to lessen the tendency to gelatinise. 

IHeterich's School Ink. Dieterich * recommends the fol- 
lowing as a cheap and effective ink for school purposes : 
200 parts of a 20 per cent, solution of logwood 
extract are diluted with 500 parts of water and heated to 
90 C. A solution of 2 parts of potassium bichromate, 50 
of chrome alum and 10 of oxalic acid in 150 parts of 
water, is then added, drop by drop, and the mixture 
maintained at 90 C. for thirty minutes, and then diluted 
to 1000 parts and mixed with i part of phenol. After 
standing for two or three days it is decanted, and is then 
ready for use. 

Hsematein Inks. Inks prepared with hasmatein in 
place of logwood extract have more brilliant shades, but 
are wanting in lustre, and are readily decomposed on 
heating. 

An alkaline hasmatein ink is prepared by mixing 12 
parts of hsematein with 720 parts of water for two hours 
at about 20 C., and then decanting the liquid, heating it 
to 30 C., and adding 3 parts of crystalline sodium car- 
bonate. When cold, 0.5 part of potassium chromate in 
48 parts of water is gradually added with constant stir- 
ring, and lastly 12 parts of gum and 0.5 part of phenol, 
with sufficient water to make 960 parts of ink in all. 

Schmieden's Acid Hcematein ink consists of 24 parts of 
haematein dissolved in water (760 parts) at a temperature 
not exceeding 39 C. ; then acidified with 80 drops of 
strong sulphuric acid, mixed with a solution of 4 parts of 
ferrous sulphate in 48 parts of water, 1 2 parts of hydro- 
chloric acid, and diluted to 960 parts, a sufficient quantity 
of gum being subsequently added. 

This ink is dark red in colour, and gives dark red 
writing, which changes to brown and then to black within 
twelve hours. 

For other formulae of logwood inks see Copying Inks, 
chap. xii. 

Use of Logwood in Patent Inks. Logwood fre- 
quently occurs as an ingredient of patented inks. Thus 
Phar-m. Manual, 1897, p. 685. 



LOGWOOD.. &c., BLACK INKS 109 

it is used in WhitfiMs Indelible Safety Ink (Eng. Pat. 
No. 7474; 1837), whilst Scott (Eng. Pat. No. 8770 ; 1840) 
prepared a similar indelible ink, consisting of a logwood 
iron ink with the adding of gum, indigo, Prussian blue, 
gas-black and iron nitrate. 

In J. Eeades patent (Eng. Pat. No. 11,474; 1846), the 
precipitate obtained by adding metallic salts (iron, copper, 
potassium bichromate) to logwood extract is incorporated 
with a printing ink. 

In 1856 (Eng. Pat. 342), C. and Gr. Swann claimed an 
ink prepared by adding potassium bichromate with a 
sufficient quantity of potassium bicarbonate, potassium 
chlorate, mercuric chloride and ammonia to a decoction of 
logwood. 

Underwood (Eng. Pat. No. 1112 ; 1857) patented a leg- 
wood copying paper (see chap. xii.). whilst logwood and 
haBmatoxylin ink powders were claimed by Cooley (Eng, 
Pat. No. 1 06; 1867), Byford (Eng. Pat. No. 974; 1876). 
and Grunwald (Eng. Pat. No. 963 ; 1881). 

Joly (Eng. Pat. No. 4484; 1875) prepared an ink by 
the action of tungsticacid upon colouring matters, such as 
those of logwood, elderberries, &c. 

Fonscca and Co. (Eng. Pat. No. 859 ; 1883) used logwood 
as an ingredient of an indelible carbon ink ; and Frusher 
{Eng. Pat. No. 8241 ; 1885) has patented the manufac- 
ture of ink from waste logwood and potassium bichromate 
from dyeing processes. 

VANADIUM INKS. 

The discovery of the fact that ammonium vanadate 
forms a black ink with gallotannic acid is attributed to 
Berzelius* but we have been unable to discover any refer- 
ence to the subject either in the Jahresberichte or Lehrbuch 
of Berzelius. The statement that this ink is of a very 
permanent character has been copied from one text-book 
to another, and is still found in different standard works 
on chemistry. 

In 1 889 Appelbaum ) made a number of experiments 

* Dlnglet-'s polyt. Journ., 1835, Ivi. 237. 
t Ibid. 1889, cclxxi. 423. 



110 INKS AND THEIR MANUFACTURE 

v:ith inks thus prepared from gall extracts and solutions 
of pure gallotannic acid, and found that both the ink 
itself and the writing faded after the lapse of a few weeks. 
Hence he doubted whether Berzelius had ever made any 
experiments with the ink. 

We have repeated the work of Appelbaum * and can 
confirm what he says about gall vanadium inks, though 
vve find that gallotannic acid gives an ink of somewhat 
greater permanency than was found to be the case by 
him. 

It has been shown by one of us (M.) that the law estab- 
lished by Schluttig and Neumann (p. 73), for iron salts 
also applies to ammonium vanadate i.e., that it yields 
black ink with substances containing three adjacent 
hydroxyl groups. Thus gallic acid, logwood extract, 
hsematoxylin and pyrogallol combine with ammonium 
metavanadate to form black inks, whilst phenol, benzoic 
acid, saccharin, &c., do not form such compounds. 

None of these inks, however, have proved satisfactory in 
our hands. Although they give an immediate black 
writing, the characters gradually turn yellow, even when 
protected from the light. Hence, apart from the question 
of expense, ammonium vanadate cannot be regarded as a 
suitable constituent of writing inks. 

It has, however, been claimed as an addition to inks in 
various patents. Thus Pinhney (Eng. Pat., No. 2745, of 
1871) prepares an ink from an aniline salt with. a salt of 
vanadium or uranium and an oxidising agent ; and a 
similar patent was taken out by G-rawitz (Eug. Pat., 
No. 1620; 1875). The use of vanadium is claimed by 
Hickisson as a constituent of a marking ink (Eng. Pat., 
No. 5122; 1878), whilst it is also used \>j Just, Weiler, 
and Heidepriem in their patent safety ink (Eng. Pat., 
16,757 ; 1890). 

Mitchell (loc. cit.) has described certain reactions of 
vanadium enabling vanadates to be readily distinguished 
from chromates, which are frequently very similar in 
colour. 

* Analyst, 1903, xxviii. 146. 



LOGWOOD, &c., BLACK INKS 111 

BLACK ANILIXE INKS. 

The formation of aniline black in a fine state of division 
within the fibres of the paper was described by Jacobsen 
as an indelible ink for writing or marking, though it has 
chiefly been used for the latter purpose. 

Various brands of nigrosine, which are the sodium salts 
of the sulphonic acids of anilidophenyl- anilidodiphenyl 
and dianilidodiphenylsafraniu-hydrochloride, are used in 
the preparation of a black writing ink. They are readily 
soluble in water, and when dissolved in the proportion of 
about i part in 80 yield a solution which flows readily, 
dries to a good black, and has no action on metallic pens, 
The solution keeps well, and the writing resists the 
action of different chemical reagents, although it can be 
removed or smudged by water, and lacks the permanency 
of good iron gall ink. 

Coupler and Collins' u Indulin ink,"* which was awarded 
a prize in Paris, was a blue-black ink which, according to 
Viedt, contained nigrosine or similar aniline dye-stuffs. 

Solutions of nigrosine were sold under the name of 
" stylographic ink " when first manufactured in 1867, owing 
to the readiness with which they flowed from stylographic 
pens. 

Particulars of other aniline inks are given under 
Coloured Inks in chap. vi. 

* Dingier 1 s polyt. Journ., 1867, clxxxiii. 78. 



CHAPTER VI. 

COLOUKED WKITING INKS. 

CONTENTS. Historical Coloured aniline inks Fugitive- 
ness of aniline inks Patented coloured inks. 

Historical. One of the earliest references to the use 
of a coloured ink is by Plutarch, who mentions a red ink 
(nvppov fiapfjia) with which certain letters were marked 
on the doors of the dikasts in Athens. Red ink com- 
pounded with minium or vermilion seems to have been 
used for the titles of books among the Romans,* whilst 
JSidonius (vii. 12) states that rubrica (red ochre) was used 
for the same purpose. It is interesting to note that our 
word "rubric," which is applied to the titles of sub- 
sections printed in red, thus finds its origin. 

A reddish-purple ink was prepared by the Romans 
from the Murex, the mollusc which yielded the famous 
Tyrian dye. Montfaucon was of opinion that this was 
the source of the ink used by the Byzantine Emperors in 
their signatures to documents. In fact, the use of any 
red ink was forbidden to any one excepting those of 
royal blood.f 

If the Emperor was still a minor, his guardians signed 
for him in green ink, the general use of which was pro- 
bably also interdicted to some extent. According to 
Astle,\ ink of this colour was frequently used in Latin 
manuscripts, though rarely found in charters ; but his 
remarks apply to later ages. 

The same authority stated that blue and yellow ink 
seldom occurred in old manuscripts, and that he knew of 
no instance of the latter being used later than 1200 A.D. 

* Ovid, Trist., I. i. 7. t Cod. Justin. I. [23], 

I Origin of Writinff, 1803, p. 209. 



COLOURED WRITING INKS - 113 

Gold and silver inks were used by both Greek and 
Roman Emperors at later periods. These probably 
consisted of the finely divided metals incorporated with 
some adhesive medium, such as gum. Metallic writing 
of this character was sometimes burnished or coated with 
wax. 

Wecker (De Secretis, 1582) gives details of the compo- 
sition of ink of different colours, and refers to gold and 
silver inks. 

In the work of, Canneparius (1660), to which we have 
frequently referred, various formulas for coloured inks 
appear, such as solution of verdigris in vinegar for green 
ink, &c. 

The use of both indigo and logwood as dye-stuffs was 
forbidden in England in the reign of Elizabeth, and the 
Act was not repealed until the reign of Charles II. (vide 
supra). After that they gradually came into use as con- 
stituents of writing inks, and are now widely employed in 
the manufacture of black writing inks. 

Inks can be made of any desired tint, for a variety of 
pigments and dye-stuffs are at the manufacturers' dis- 
posal ; and the discovery of the coal-tar colours, to which 
the main credit is due to Perkin, has increased their 
resources almost indefinitely, for they are now able to 
match any ray of the solar spectrum. Before the time of 
alizarine and aniline (1858) the maker of coloured inks 
had recourse to the various vegetable and mineral pro- 
ducts which have been used from time immemorial for 
dyeing fabrics. Thus for red he would employ Brazil 
wood and cochineal, the latter having a disadvantage in 
the circumstance that caustic ammonia in considerable 
quantity is necessary to dissolve it, so that it shall remain 
in solution and now freely from the pen. But cochineal 
or carmine inks were expensive, and they, together with 
Brazil wood and tin-salt red inks, ceased to be manufac- 
tured to any great extent when the more brilliant coal- 
tar colours became available. 

Older Formulae for Coloured Writing Inks. The 
following recipes, taken from various sources, are typical 
of the kind of coloured ink prepared from pigments other 
than aniline dye-stuffs : 

H 



114 INKS AND THEIR MANUFACTURE 

Eed Inks. (i) Cochineal, i oz. ; ammonia, i oz. ; 
and water, i quart ; the infusion being decanted after 
three days, diluted with water to the required intensity of 
colour, and a little antiseptic added. 

(ii) Brazil wood (powdered), i Ib. ; acetic acid (5 per 
cent, strength), i gallon, boiled until of sufficient colour, 
and the extract mixed with 8 oz. of gum, 8 oz. of 
alum, and a little antiseptic. 

Green Inks. (i) Cream of tartar, 1 part ; verdigris, 
2 parts, boiled with 8 parts of water. 

(ii) Copper acetate, i oz. in i pint of water, 
(iii) Potassium chromate, 10 parts; hydrochloric 
acid, 10 parts; alcohol, 10 parts; water, 30 parts. 
Neutralised with sodium carbonate after reduction to 
the chromic salt, mixed with 10 parts of gum, and 
decanted ( Winckler). 

(iv) Indigo ink mixed with a 1.25 per cent, solution 
of picric acid (Stein). 

Blue Inks. (i) Freshly precipitated Prussian blue 
triturated with a tenth of its weight of oxalic acid, 
and water gradually added. 

(ii) Indigo carmine, 10 parts; gum, 5 parts; in 75 
parts of water. 

Purple Ink. Infusion of logwood mixed with copper 
acetate, gum arabic and alum (Normandy). 

Violet Ink. Indigo blue ink mixed with cochineal ink. 
Yellow Inks. (i) A decoction of 25 parts of .^Persian 
berries (Rhamnus amygdalinus, &c.) in 100 parts of a 
3 per cent, solution of alum mixed with 4 parts of gum. 
(ii) A solution of gamboge in alcohol (10 : 10) mixed 
with 5 parts of gum and diluted to 30 parts with water, 
(iii) A 10 per cent, solution of picric acid containing 
2 per cent, of gum. 

In a Report to the Science and Art Department in i888/ 
Dr. Russell and Sir W. Abney summarised the results of 
their experiments on the stability of various water-colour 
pigments exposed for two years to the action of light and 
dry air. In each case a wash of 8 tints was applied to 
paper of the same size and quality, and the slips enclosed 
in glass cylinders, so arranged that free circulation of air 
took place whilst dust was excluded. 



COLOURED WRITING INKS 115 

In the following list, based on these results, the different 
pigments are arranged in the order of their instability, 
whilst those showing a distinct change in hue or depth of 
colour are marked with an asterisk: Carmine,* ciimson 
lake,* purple madder,* scarlet lake,* Naples yellow,* olive 
green,* indigo,* brown madder,* gamboge,* vandyke 
brown,* Indian yellow,* cadmium yellow, sepia,* aureolin, 
roc- madder, permanent blue, Antwerp blue, madder lake, 
vermilion, emerald green, burnt umber, yellow ochre, 
chrome yellow, raw sienna, Indian red, Venetian red, 
burnt sienna, chromium oxide, Prussian blue, cobalt, 
ultramarine ash. 

When exposed to the action of moist air very few of 
the pigments remained unaffected, and none of those of 
organic origin, whilst the Prussian and Antwerp blues 
were completely destroyed. 

Experiments were also made in which the washes of 
pigment were protected from the action of atmospheric 
oxygen and moisture. The vermilion turned black, but 
this change was attributed to a physical and not to chemi- 
cal alteration. 

In a later series of experiments, to quote Sir W. Abney's 
words : 

" We took exactly similar tubes, dried the papers very 
carefully indeed, dried the tube, inserted the papers, put 
a Sprengel pump to work, and made a vacuum, and then 
when the vacuum was very complete, sealed off the top 
and exposed them." Under these stringent conditions 
only five colours were acted upon in the very least, and the 
amount of change was almost imperceptible. The five that 
were changed were vermilion, raw sienna, Prussian blue, 
purple madder, and sepia. 

COLOURED ANILINE INKS. 

Aniline Inks. Any conceivable kind of red tint, from 
magenta to the most brilliant scarlet, can now be obtained 
from the makers of coal-tar colours, and the writers have 
to acknowledge their indebtedness to the Badisclie 
Company, Ltd., for their courtesy in supplying full infor- 
mation as to the most suitable dye-stuffs, and sending 



116 INKS AND THEIR MANUFACTURE 

specimen samples for testing. Some of these colours are 
more fitted for ink manufacture than others, those which 
are the more readily soluble in water being naturally the 
best. The red, known as eosine, which was discovered by 
Caro in 1874, was early recognised as a valuable material 
for the purpose, and appears to be more used than any 
other dye-stuff. In aqueous solution eosine is subject to 
the formation of a fungoid growth, so that a small quantity 
of an antiseptic must be added to the ink to keep it in 
good condition ; otherwise its rich colour is liable to change. 

As in the case of red inks, the manufacturer has a 
number of different tints of blue to choose from in the coal- 
tar colours. They are most tempting substances to employ, 
for the suitable ones form a true solution with water, and 
as a general rule nothing beyond water is required to 
convert them into serviceable inks. The first aniline 
colour which was tried for the purpose was Hofmann's 
violet, discovered in 1863, a dye-stuff of such high tinctorial 
value that an ink composed of one part of it in 200 parts 
of water not only gives a most vivid colour, but will afford 
by pressure three or four good copies. 

Fugitiveness of Aniline Inks. Instances of the 
instability of ink of this character, which is largely 
employed for typewriting, are given in a letter to the 
Scientific American (Ap. 18, 1903). The writer states that 
typewritten documents, after being stored for six months 
in a slightly damp place, were illegible, with the exception 
of the gall ink signatures. 

In another case a letter-book was wetted with water 
used to extinguish a fire, and the signatures (in gall ink) 
were all that remained of IOO pages of correspondence. 

It has also been shown by Cross and Bevan * that all the 
aniline colours when dyed on fabrics fade more or less on 
exposure to sunlight, whilst eosine and methylene blue 
are specially fugitive. 

The following table of certain aniline dye-stuffs suitable 
for coloured writing inks is based on information supplied 
by the Badische Company, Ltd. 

See also Aniline Black Inks, chap. v. ; Copying Inks, 
chap. xii. ; and Ink Powders, chap. xvi. 

* Journ. Soc. Arts, 1891, xxxix. 152. 



COLOURED WRITING INKS 117 

Aniline Dye-stuffs suitable for Writing Inks. 



Colour. 


Trade name. 


Scientific. 


Bed. 


Eosine, erythrosine 
and phloxine. 

Ponceau scarlet. 
Cotton scarlet. 


Alkali salts of bromine and iodine 
compounds of fluorescein and of 
dichlorfiuorescein. 
Alkali salts of xylidin-azo- and 
cumidiu - azo - naphtholdisulphonic 
acids. 
Sodium salt of amido-azo-benzol-azo- 
naphtholdisulphonic acid. 


Green. 


Neptune green S.G. 
Light green S.F. 
(yellowish). 

Light green S.F. 
(bluish). 
Diamond green G. 
&B. 


A triphenylmethane dye-stuff. 
Sodium salt of diethyl-dibenzyl-dia- 
midotriphenyl carbinol trisulpho- 
nic acid. 
Sodium salt of the dimethyl com- 
pound. 
Salts of tetra-ethyl- and tetra-methyl- 
di - para - amido - triphenyl carbi- 
drides. 


Blue. 


Indigo carmine. 
Soluble blue T. 


Indigotin sodium disulphonate. 
Salts of triphenylrosanilin and tri- 
phenylpararosanilin - trisulphonic 
aeids. 


Violet. 


Acid violet 46. L. 


Sodium salt of tetraethyldibenzyl- 
pararosanilin-disulphonic acid. 


Yellow. 


Fast yellow. 
Tartrazine. 


Mixtures of the sodium salts of 
amidoazobenzoldisulphonic, mono- 
sulphonic, and amido-azotoluoldi- 
sulphonic acids. 
Sodium salt of diphenyl-parasulpho- 
nic acid or of azo-dioxytartaric 
acid. 



The usual proportions that we have found to yield suit- 
able solutions for writing inks are about I gramme in 50 
to 80 c.c. of water, according to the tinctorial power of 
the particular dye-stuff. The inks thus made are very 
fluid, and in this respect particularly suitable for stylo- 



118 INKS AND THEIR MANUFACTURE 

graphic and other descriptions of fountain pens. If a 
suitable dye-stuff be used there will be no precipitation, and 
therefore no suspension of particles in the liquid. There 
is, therefore, no need to add gum to inks of this description ; 
indeed, such an addition would tend to counteract one of 
their most valuable properties their fluidity. It is neces- 
sary to mention this point, because we have found many 
published formulae for aniline inks in which sugar or gum 
is erroneously included as a necessary constituent. 

Patent Coloured Inks. Reade, in his patent (No. 
1 1,474, 1846), claimed the use of inks containing a soluble 
Prussian blue," prepared in a specified manner, and of a 
red ink prepared from cochineal. A lake of cochineal 
extract and alum dissolved in ammonia solution was also 
claimed by Wood in 1885 (Eng. Pat., No. 1676). 

The use of aniline dyes was first claimed in this country 
by Crocin 1861 (Eng. Pat., No. 2972), and in the following 
year by Annaud (Eng. Pat., No. 675, 1862). Pigments 
from aniline waste were proposed as the source of writing 
inks by de la Rue (Eng. Pat., No. 2235, 1862), whilst 
aniline dye-stuffs were again patented by Jefferies in 1 879 
(Eng. Pat., No. 3391). For or/her patents in which 
coloured pigments are claimed see Copying Inks, Sympa- 
thetic Inks and Ink Powders. 



CHAPTER VII. 

EXAMINATION OF WKITING INKS. 

CONTENTS. Fluidity of ink Penetration through paper- 
Stickiness of writing Composition of commercial inks 
Schluttig and Neumann's stripe test Acidity, action on steel 
pens Stability on keeping Examination of handwriting 
Old manuscripts Palimpsests Forged handwriting 
Bleaching agents Differentiation of writing done with different 
inks Photographic methods Mechanical erasure Chemical 
removal of writing Destruction of sizing Alterations and 
additions to writing Photographic distinction between dif- 
ferent inks. 

THE number of substances entering into the composition 
of ink is very large ; but since the influence of many of 
these on the permanency of the writing is unknown, a full 
analysis of an ink would not afford much information, at 
any rate as compared with the results of practical tests. 

One of the rules of the German Versuchsamt is that an 
ink for documentary purposes shall contain a certain mini- 
mum proportion of tannic or gallic acids derived from galls 
(vide infra). It has, however, been shown conclusively by 
Schluttig and Neumann, who submitted samples of dif- 
ferent inks to the office for examination, that the chemical 
tests employed are quite incapable of identifying an ink 
prepared (e.g., from chestnut bark), and they therefore 
contend that an ink prepared from tannic or gallic acid 
derived from any source should be permitted in inks of 
Class I. 

The requirements of a good ink are : (i) It must yield 
permanent writing which becomes black within the course 
of a few days ; (2) It must flow readily from the pen, and 
penetrate well into the fibres of the paper, without passing 
right through the paper; (3) It must not gelatinise or 
become mouldy in the ink-pots ; (4) It should have a 



120 INKS AND THEIR MANUFACTUEE 

minimum corrosive action upon steel pens ; (5) The writing 
must not be sticky (except in the case of some copying 1 
inks). 

Fluidity of Ink. Schluttig and Neumann recommend 
their stripe test (p. 121) as a means of determining the 
capacity of an ink to flow readily from the pen without 
spreading too freely on the paper. At the point where the 
glass pipette touches the paper in their test, an oval head 
to the stripe is formed, whilst the remainder of the stripe 
is nearly as wide. Of 8 1 inks examined by Scliluttig and 
Neumann, the majority gave the same results as the typical 
ink, whilst the copying inks yielded somewhat narrower 
stripes. Inks flowing too readily, however, produced a 
much wider head, whilst the lower part of the stripe was 
contracted to a narrower band than the others. 

We have found a simple viscosimeter, consisting of a 5oc.c. 
pipette to give concordant results when used in the follow- 
ing manner. The pipette is standardised on distilled water 
at 15.5 C., the time required for the liquid to run down to 
a given mark on the lower stem being taken as unity. The 
ink is then brought to the same temperature, and the time 
taken for the same volume to run out determined in the 
same way. Thus, in a pipette from which the water ran 
out in 40 seconds, we found that different writing inks 
required from 42 to 55 seconds, whilst copying inks in some 
cases required 70 seconds. 

Penetration through Paper. This is best determined 
by a practical test on standard paper, under the same con- 
ditions as used with the typical standard ink. The ink 
should penetrate into the fibres, but should not come 
through the paper. 

; Stickiness of Writing. Here, again, the best results 
are obtained by comparison with a typicalink, as recom- 
mended by Scliluttig and Neumann. 

Composition of Commercial Inks. The following table 
gives the results of partial analyses of certain well-known 
commercial inks. It will be seen that the blue-black inks 
of the three different manufacturers are very similar in 
character. 



EXAMINATION OF WKITING INKS 121 















Efflux 


Ink. 


Specific 
gravity 


Water. 


Total 
solid 


Ash. 


Iron. 


viscosity 
(Water 




at 

r * ,- f^ 




matter. 






at 15.5 C. 




I 5-5 c - 










= 40 














seconds). 






Per cent. 


Per cent. 


Per cent. 


Per cent. 


Seconds. 


i. Blue-black I. 





96.21 


3-79 


0.764 


0.32 





2. I. 


1.0206 


96.42 


3-58 


0.767 


0.32 


5 2 


3- ' II. 


1.0214 


96.44 


3-56 


0.90 


027 


49 


4. Chrome ink 





98.70 


1.22 


0.26 




42 


5. "Japan" ink . 


1.0413 


92.74 


7.26 


2.18 


0.84 


55 


6. Blue-black III. 


1.0141 


97-44 


2.56 


0.58 


0.23 


43 


7. Black ink (log-- 














AVOOd) . 


1.0115 


97.86 


2.14 


1.04 


0.14 


43 



A qualitative test that sometimes enables one to dis- 
tinguish between inks of different makers is their behaviour 
on titration with a saturated solution of bromine water. 
Thus, the blue-black ink I. became first dirty grey, and 
then greyish-black ; whilst No. II. first changed to violet 
and became turbid brown on. the further addition of the 
reagent ; and No. III. first became violet and then dirty 
green, the liquid remaining clear all the time. This last 
ink was also characterised by the ash being very difficult 
to burn white, and being then extremely insoluble in 
hydrochloric acid. 

The presence of logwood in an ink is readily identified 
by the colour changing to bright red on the addition of 
hydrochloric acid (see p. 104). When indigo is also 
present the hydrochloric acid gives a purple colora- 
tion. 

Indigo increases the stability of an ink towards bleaching 
agents such as bromine water. An ordinary iron gall ink 
is rapidly decolorised on tbe addition of strong hydro- 
chloric acid, but if indigo be present the liquid remains 
blue, even after being boiled with the reagent. 

Schluttig and Neumann's Stripe Test. For comparison 
in their colorimetric method, Schluttig and Neumann make 
use of a standard ink containing the following con- 
stituents : Gallotannic acid, 23.4 grms. ; gallic acid, 7.7 
grms. ; gum, 10 grms. ; hydrochloric acid, 2.5 grrns. ; and 
ferrous sulphate, 30 grms. in a litre of water. After 



122 INKS AND THEIR MANUFACTURE 

standing for not less than four days, this ink is decanted 
and kept in a well-corked bottle. 

In testing an unknown ink, 10 to 15 c.c. are compared 
with the standard ink, and should there be a difference in 
shade a small quantity of one or more suitable aniline dye- 
stuffs is added to the standard, so as to make the colours 
match. 

The apparatus required consists of a frame over which 
is tightly stretched a piece of best writing paper. This 
frame is fixed at an angle of 45, and the unknown ink is 
allowed to run down this from a special pipette delivering 
exactly 0.6 c.c. A similar stain is made with the ink after 
dilution with an equal quantity of water, and also with the 
standard ink before and after dilution. 

When the ink is dry the paper is set aside in a place 
exposed to light and air, and after eight days the stains 
are compared with the standard stains with regard to their 
colour, whilst their shape also gives an idea of the fluidity 
of the original ink. The paper is also to be cut in strips 
horizontally and one piece immersed in water, another in 
alcohol of 85 per cent, strength, and a third in alcohol 50 
per cent, strength for several days. If the stripe of any 
particular ink becomes paler than that of the typical ink 
under these conditions, ScJiluttig and Neumann conclude 
that the former is either too poor in gallic or tannic acid, 
or contains too much acid. 

The objects of repeating the test after dilution are that 
the added aniline colours have less disturbing influence in 
the diluted ink, that differences of intensity are more pro- 
nounced, and that differences in the breadth of the stripes 
given by copying inks are reduced to a minimum. 

Schluttig and Neumann do not contend that all inks must 
have the composition of their typical preparation, but 
assert that while containing at least 0.6 per cent, of iron, 
they must give equally satisfactory results in the different 
tests. 

In place of the somewhat complicated apparatus devised 
by Schluttig and Neumann, we have found that sheets of 
Bristol board placed on a wooden stand fixed at an angle 
of 45 give satisfactory and concordant results in this 
test. 



EXAMINATION OF WRITING INKS 123 

Acidity : Action on Steel Pens. It is not an easy 
matter to determine the amount of free acid in an ink by 
titration on account of the colour of the ink itself masking 
the change of colour of the indicator. It is possible, 
however, to obtain approximately correct results by 
diluting the ink with a very large volume of water and 
titrating with standard alkali, using phenol-phthalein as 
indicator. Thus in the case of a well-known blue-black 
ink we found that the acidity of 10 c.c. of the ink corre- 
sponded to 3. 1 c.c. of normal alkali. 

Another practical test is to immerse a steel pen in the 
ink for a given period, and to determine the loss in weight. 
Thus in the case of the ink referred to above we found 
that a pen had lost 5.18 percent, of its weight after being 
kept in 10 c.c. of the ink for a month, whilst the ink 
itself had become nearly solid. 

It is thus evident that the contention of Schluttig and 
Neumann * that free acid does not act upon metals in the 
presence of tannin is not justified by the results of ex- 
periments. 

Schluttig and Neumann consider that it is not possible 
to fix a maximum amount of acidity. They recommend 
their stripe test as the best means of determining whether 
too much acid is present, since ink darkens more slowly 
the greater the proportion of acid. Thus, if the stripes 
are as intense a black in as short a time as those given by 
their standard ink. they consider the amount of acid as 
not too great. 

Stability on Keeping. A good ink will frequently 
keep as long as a year without throwing down any in- 
soluble deposit on the sides of a vessel provided air be 
excluded. At the same time, if a sample bottle contain 
some deposit, the ink is not necessarily of bad quality, 
since this may be due to changes of temperature. Should 
there be a pellicle, however, in a sample bottle the ink 
should be rejected as inferior. 

Schluttig and Neumann have devised the following test 
for determining the stability of an ink in a comparatively 
short time : The bottle containing the ink is allowed to 

* loc. cit. 



124 INKS AND THEIR MANUFACTURE 

stand for three days at a temperature of 10 to 15 C., 
after which 50 c.c. are withdrawn from the centre by 
means of a pipette without shaking the contents. This is 
filtered and 25 c.c. of the filtrate placed in a cylindrical 
glass vessel about 185 mm. high and 72 mm. in diameter, 
the mouth of which is then covered with paper to exclude 
dust. ^ ';.;"- 

Sclduttig and Neumann's typical ink when thus tested 
remained unchanged for three weeks, after which a pellicle 
began to form on the surface, and small flecks to separate 
Oilt- 'This ink was obviously purer than ordinary com- 
mercial inks, many of which, however, remained unchanged 
for fourteen days or longer, and in Scliluttig and Neu- 
mann's opinion this period should be fixed as the minimum 
keeping time for an ink of the first class under these 
conditions. 



EXAMINATION OF HANDWRITING. 

Old Manuscripts. We have already pointed out that, 
although in many ancient manuscripts the writing is as 
distinct as when first written, there are also numerous 
cases in which the characters have faded to such an extent 
as to be almost illegible. 

Numerous methods have been suggested for restoring 
tte intensity of the original writing, but many of these 
are open to the objection that they injure the surface of 
the material. 

The oldest and best known of these methods was to 
sponge the writing with an infusion of galls, the tannin 
of which would once more combine with the iron left in 
the paper, thus forming a fresh ink. This method was 
described in the book of Canneparius in 1660. 

A much more reliable method was that first proposed 
by Blagden in 1787, which was based on the formation of 
a blue compound by the action of a solution of potassium 
ferrocyanide and dilute hydrochloric acid on the residual 
iyon in the paper. This affords an easy means of dis- 
tinguishing between carbon inks and iron gall inks, and 
Blagden was thus able to show that the writing on certain 



EXAMINATION OF WRITING INKS 125 

vellum manuscripts of the ninth and fifteenth centuries 
consisted of iron ink. 

Lenher's method of applying this process of restoration 
is to immerse the paper for a few seconds in one per cent, 
pure hydrochloric acid, and to allow it to dry spontaneously. 
The writing is then dusted over with powdered potassium 
ferrocyanide, and covered with a glass plate on which is 
placed a weight. After being left for a few hours the 
paper is thoroughly dried, and the excess of ferrocyanide 
removed by means of a soft brush. 

A more modern and less drastic method is to use a 
solution of ammonium hydrosulphide, which is applied 
foV a few seconds until the writing becomes darker, and 
is then sponged off as rapidly as possible after the desired 
effect is obtained. 

In this method the basic ferric salt into which the ink 
in the paper had decomposed is converted into the black 
ferrous sulphide. Writing thus restored may speedily be 
reoxidised so as to nearly disappear again, and the method 
can only be regarded as a temporary expedient. Lenher * 
has devised the following means of keeping writing thus 
restored for a longer period : The damped paper is sup- 
ported on a frame of threads fixed half way up in a 
shallow box (four inches deep), whilst ammonium sul- 
phide is placed in a small dish beneath. The box is 
closed by a glass cover, and after a short time the vapours 
of ammonium sulphide act on the writing, which becomes 
first brown and then black, and retains its intensity so 
long as the manuscript is left in the box. 

Palimpsests. The name palimpsest is derived from 
the Greek words 7ra\iv = again, and Tro-ftrroc = rubbed. 
It is applied to old manuscripts, the parchment of which 
had been previously used for a similar purpose. This 
practice was doubtless due to the cost of new material. 
The first writing on the skins was obliterated by means 
of pumice or some other abrading substance, but the 
mechanical action was insufficient to remove characters, 
possibly written three or four centuries earlier. In cases 
where the iron constituent of the ink had sunk deeply into 

* Die T'uiten Fabrikation, p 144. 



126 INKS AND THEIR MANUFACTURE 

the vellum, it would be almost impossible completely to 
eliminate it, and the use of the reagents described above 
would reveal the original characters. 

Morides' Process. This consists of softening the skin 
by leaving it in distilled water, then treating it with a one 
per cent, solution of oxalic acid to bring the residual iron 
in the paper into a soluble state, again rinsing it in water 
and immersing it in a one per cent, solution of gallic acid, 
which will again form ink with the iron. Finally, the 
parchment is washed in water and pressed between blot- 
ting paper. Care must be taken to avoid an excess of 
oxalic acid, which might completely destroy the writing, 
and the method has the further drawback that the parch- 
ment is sometimes blackened all over by the gallic acid. 

Lenher advocates exposing the parchment to steam and 
then to acetic acid vapours before applying the gallic 
acid. 

It may also be noted here that photography affords a 
ready and most efficient means of deciphering such parti- 
ally obliterated writing, the pale yellow colour of the iron 
oxide from the old ink appearing black in a photographic 
copy. 

FORGED HANDWRITING. 

The police reports abundantly prove that the crime of 
forgery frequently engages the attention of our magis- 
trates. This is not surprising when we remember that 
the means are in the hands of every one, and that bankers' 
cheques are a common medium of exchange. The usual 
evidence called by the prosecution is that of the hand- 
writing expert, who bases his opinion on the form and 
peculiarities of the caligraphy. We are inclined to think 
that much more stress might in many cases be laid upon 
the chemical aspect of the question. What we mean is 
that in a case where additional letters or figures have been 
added to, say, a banker's draft, it would be comparative!}* 
easy to ascertain whether the interpolated characters had 
or had not been written with the same ink as that used 
for the body of the document. When there is any objec- 
tion to bringing chemical reagents in contact with the 
original paper, the camera can be employed in the way 



EXAMINATION OF WRITING INKS 127 

first brought into prominence by Dr. Paul Jeserich, which 
we describe at length in a subsequent page. 

Bleaching Agents. It is possible to remove completely 
all traces of an ink stain (not containing carbon) by the 
use of suitable bleaching reagents, among which may be 
mentioned solutions of chlorine, bromine, acidified bleach- 
ing powder, &c. 

Traill, in the course of his research into the permanency 
of inks, tested the effect of various reagents on the writing 
done with ordinary iron gall ink, and classified them into 
the following groups : 

I. Those completely effacing the writing : 

Solutions of chlorine ; chloride of lime with weak acid ; 

antimony chloride ; dilute aqua regia ; and oxalic acid. 
v IL Those effacing the writing to a large extent : 

Dilute nitric, sulphuric, and hydrochloric acids. 

III. Those rendering the writing faint : 

Solutions of potassium and sodium hydroxides and 

ammonia. 

To the first group we may add the following sub- 
stances : Bromine, sulphur dioxide, sodium nitrite with 
hydrochloric acid, and citric acid ; whilst hydrogen per- 
oxide solution and potassium bisulphate speedily render 
the writing very faint. 

As has been already mentioned, the addition of indigo 
to iron gall ink renders it much more resistant to the 
action of these reagents. 

Differentiation of Writing done with Different Inks. 
If writing from various sources be subjected to a system- 
atic series of tests differences in that done with different 
inks, or even at different periods, will generally be 
observed. For instance, in the case of the reagents used 
by Traill (supra), fifty envelopes were tested, and th& 
writing on no two of them gave identical results. 

Robertson and Hoffmann * employed the following 
reagents for distinguishing between writing done with 
different kinds of ink. In each case a feather was dipped 
in the reagent and a note taken of any change occurring at 
the junction of the ink and paper. 

* Eisner, Die Pi-axis der Chemiker, p. 598. 



128 , INKS AND THEIE MANUFACTURE 



Resorciu ink. 


Bright red. 
Bleached. 


oj 

02 

g 


03 


1 1 d-Sd 

'o o | D | 

s 1 ^1^ 


03 


Unaltered. 
Brown. 


M 


1 




. 


'd 




tf 


~| 
I 


1* 

a- 


flJ 


2 i-Q 


3 S IllfS 1 

02 ^ S >, 

pQ 02 M 


"Is 
a 
p 


^ fcJD S 
pQ ^ -IS 


> 


02 






H> 




Q 


a 


g 




-d 


; i\ 


d 


,2-d '. 




fcJO r2 


iD l _^* r ^ 




< 0-3 j^ O "I? 


03 


o as a 


ft 


a rO 


Pi 


5 

1 


"5^ p Q ^ 

= M |l 


1 

Is 
a 
P 


-< be S 

>r& ^ 
^ 3 S 

|. 


'It 


p. 


o 


1 

'Hi 


p g f P 44 


1 

^03 


it'L 

*! 


5 


5 


o 

5 


3 

PH 


cl 


1 


P 02 'OJ 

H 


O 




-d 




^ d -d- 




. 


-- * 


^J 


03 




S ^ 9^ 




d 03 


1! 


1 * 


JO 

. 3, 

O-i 


1 


**! II 


73 

i 


1 1 

PP ,2 
PQ 


g 


1 


"03 a 


4 


^d 




O U 


1 




1 fi 


si 

a to 


i 


6 6 6 ^ 'o ^ 
ppp .g>j 


s 


j* 




pq 


eS 


pq 


^^P 




p S 












1-1 . 3 o "^ ** 


03 PH 


^ 




o^~ o 


"o 


O 


oT M co- ^.ai^ 


e3 C 


13 N 


I 




1 1 


is 
.2 


1 


I Hfl | ll 


Jf 


XI 03" 

O r 


^ 


H C3 


j^ O 




C^ ^ -2 QC r5 "^ ^ 




r^ ._ Q 


PH 


.2 o 


S 1 - 1 




o w -n' 73 ^ -g 'a 




rH 








^3 




s F"^ 


-I S ^ 




1 a 


t& 


"3 


8 Ft" I is 

O2 O2 02 


PH 


'5'i i 
+ - g 



f 






d ^ 

1-J 4"<t 



EXAMINATION OF WRITING INKS 129 

In Fig. 29 we show the results of testing the writing 
done with different commercial inks with certain bleaching 
reagents. 

Obviously these tests can only be looked upon as typical 
examples, for numerous other substances are added to 
modern inks, and each of these may play a part in 
modifying the reaction given by any particular reagent. 

For the detection of forgeries in documents Chevallier * 
recommended the following systematic series of tests : (i) 
Examination of the surface of the paper with a magnify- 
ing glass ; (2) treatment with distilled water ; (3) with 
alcohol ; (4) with blue and red litmus ; and (5) with 
various chemical reagents. 

i. The colour of the ink is noted and any irregularities 
in the edges of the characters. If there has been any 
mechanical treatment the paper may appear thinner iu 
some places than in others. 

ii. Water may be absorbed more rapidly by^ one part 
than another. 

iii. The object of the alcohol test is to detect removal of 
the size in the treatment which removed the writing. 
The writing on the rubbed part spreads out more and 
penetrates into the paper. Skilful forgers have employed 
rosin and glue to restore the surface of the paper. To 
detect this the paper is first treated with hot water and 
then with alcohol. 

iv. The moistened document is placed between sheets of 
blue or red litmus on which is placed a weight, and a note 
taken of any change in colour and whether it is uniform. 

v. The writing is moistened and treated with various 
intensifying reagents such as gallic acid, potassium ferro- 
cyanide, alkali sulphide, or hydrogen sulphide, the treat- 
ment being repeated after twenty-four hours. Some- 
times prior writing appears after the lapse of ten to thirty 
days. 

Chevallier and Lassciigne ( advocate the use of iodine 
vapour applied to the moistened paper, a blue spot appear- 
ing where the sizing has been erased, whilst the remainder 
of the surface becomes brown. 

* Dingier^ poly t. Journ., 1832, xliv. 131. 
f Eisner, loc. cit., p. 600. 



130 INKS AND THEIR MANUFACTURE 

The spots are then best treated with sulphur dioxide 
solution, then with a 3 per cent, solution of hydrogen 
peroxide, and lastly with ammonia. After removal of 
the excess of the last reagent tannin may be used to 
render any characters darker and more visible. 

Potassium fluoride does not act upon indigo or aniline 
blue ; but if characters made with Prussian blue be mois- 
tened with the solution and steam passed over them, white 
flecks appear. 

Photographic Methods. During the last twelve years 
considerable attention has been directed, especially on the 
Continent, to the application of the camera to the detection 
of alterations in manuscripts and printed matter. The 
chief advantages of photographic methods over chemi- 
cal tests, if equally efficient, are that the document 
under examination is not affected in any way, and that 
details can be magnified to any required extent for closer 
examination. The latter consideration is of special im- 
portance in cases where a document forms the subject of 
inquiry before a court of law, and where it is necessary to 
demonstrate its characteristics to a judge and jury. 

Mechanical Erasure. We have previously noted that 
any obliteration of writing by mechanical means can 
almost invariably be detected by the eye, owing to the 

freater transparency of that portion of the paper, 
uch thinning of the paper would be detected still 
more surely by photographing it by transmitted light, 
the local injury appearing on the negative as a blot of 
greater density. If photographed in direct light the 
abrasion would probably not be apparent. If, on the 
other hand, the light were allowed to fall obliquely 
npon it, the roughened fibres would stand out distinctly 
unless some special means had been adopted for con- 
cealing the injury (vide supra). 

Chemical Removal of Writing. The slight yellow 
stain which is usually the effect of removing writing by 
the application of chemical reagents, though hardly 
noticeable to the naked eye, will be accentuated in the 
photographic negative. 

Destruction of Sizing. When writing has been re- 
moved by mechanical or chemical means, the size or 



EXAMINATION OF WRITING INKS 131 

other dressing on the paper may be simultaneously 
removed. This again would often be invisible to the 
eye, but would be readily revealed by the camera, for 
any ink marks on the rough places would spread to a 
certain extent over the now unshielded fibres of the 
paper. An enlargement of a few diameters only would 
render manifest the rough edges of the lines. 

Alterations and Additions to Writing. It is not diffi- 
cult for a skilful forger to alter letters or figures so as 
to deceive the casual observer. Thus a o might be 
turned into a 6 or 9, or the word " eight " changed to 
"eighty." These alterations would be detected by a 
photographic enlargement. 

Photographic Distinction between Different Inks. 
Jeserich * was the first to assert that inks apparently black 
were really brown, blue, or red in tint, when dry upon 
the paper ; and that such differences were clearly shown in 
an ordinary photographic negative, and still more so in 
one taken by the isochromatic method. This statement 
has been repeated by Minovici,^ and quoted in different 
journals. 

We have made experiments as to this point, writing a 
series of words with different commercial inks. Differences 
of intensity were distinctly visible to the eye, and the 
photograph taken on an ordinary plate by daylight revealed 
no more. 

We have also photographed the same writing with a 
Cadett spectrum plate and "Absolutus" screen, without 
attaining any different effect. It is evident that this 
method, even if it yield good results in particular cases, 
is not generally applicable. 

* Journ. Roy. Phot. Soc. 

t Bull, delta Soc. Fotograf. Italiana, 1900, xii. 349. 



SECTION II. 
PRINTING INKS. 

CHAPTER VIII. 

EARLY METHODS OF MANUFACTURE. 

CONTENTS. Historical China Greece and Rome England 
Early printed books Early methods of manufacture Fertel's 
method of making ink Breton's method Savage's method of 
manufacture Mod.ern methods of preparing ink. 

Historical. China, A work which is said to have been 
written during the reign of Wu Wang, about 1200 B.C., 
makes mention of the blackening of engraved characters, 
but it does not seem to be clear whether this refers to 
inscriptions on stone which would be thus rendered more 
legible a method still in use by monumental masons or 
to blocks to be afterwards used to yield impressions upon 
another surface. It seems certain, however, that a primi- 
tive mode of printing was known by the Chinese as early as 
50 B.C., but that not much advance was made until the 
reign of Ming-Tsung, 927 A.D., when certain volumes were 
printed from stone blocks for the Imperial College at 
Pekin. In this early example of the printer's art the 
characters were cut into the surface of the stone, so that 
when printed they would appear as white on a black 
ground. Shortly afterwards engraved blocks of wood, 
with the letters in relief, were used for another edition of 
the same work. In the eleventh century an ingenious 
Chinese block was made, with cut or moulded characters 
in cubes of porcelain, and these, after being baked to 
harden them, were pressed into a block of cement so that 






EARLY METHODS OF MANUFACTURE 133 

they could be printed from. The method was not fol- 
lowed up. 

The adoption of movable types in China was rendered 
difficult for the reason that in the Chinese language the 
words cannot be resolved into the letters of an alphabet. 
Each word requires a separate character, and as there are 
about 80,000 of them, of which, however, only 14,000 to 
15,000 are in common use, the Chinese printer must be a 
man of exceptional agility. Nevertheless, a large number 
of books and periodicals are now printed in China. It is 
obvious that the Chinese had only to add varnish to tLe 
black pigment familiar to them in order to compound a 
good printing ink. 

Greece and Rome. Although both the Greeks and 
Romans were acquainted with the art of engraving on 
metals at a very early period, there is no trace of any 
attempt being made to transfer designs so cut to other 
substances, if we except certain stamps which were 
employed to mark bricks and articles of pottery. There 
was no inducement to stimulating invention in this direc- 
tion while slave labour could be employed for writing 
documents, and we can easily imagine that with the decline 
of Rome literature would only be cultivated by the very 
few. But as soon as paper began to be known, and was 
recognised as a unique material for epistolary corres- 
pondence, and for the making of books, the minds of many 
must have instinctively turned to the possibility of 
multiplying copies by an engraved surface, and an impres- 
sion-giving medium. 

England. Caxton came to England and set up a press 
in Westminster about A.D. 1477 (the exact date has not 
been ascertainable), but the first paper mill was not estab- 
lished in England until 1498. The printing press was 
therefore ready nearly twenty years before the means ex- 
isted in this country of supplying it with its first requisite. 
But in Italy and Germany paper mills were at work in the 
thirteenth century, and in France, Switzerland, and Austria 
in the fourteenth. The arts of printing and papermaking 
naturally reacted upon one another for the advantage of 
each, and the Chinese are believed to be the first nation 
which benefited by their partnership. 



134 INKS AND THEIR MANUFACTURE 

Early Printed Books. Many examples of early printing 
can be seen in the galleries of the British Museum ; and 
it is interesting to examine the specimens displayed in 
cases in the King's library there, if only to note the manner 
in which they have, with very few exceptions, preserved 
their pristine appearance. 

Block Books. Beginning with the block books, i.e., 
books in which both cuts and letterpress were cut on solid 
wood blocks, we find that the earliest bears the date 1470* 
and we learn from the catalogue that " the long-accepted 
belief that letter-printing from the solid block was 
necessarily prior to that from movable types, and must 
therefore have been introduced by about 1440, is now 
seriously challenged." 

The block book was only used for works of a popular 
character, and answered the purpose of the modern 
stereotype block from which a number of copies can be 
printed without the necessity of resetting type. These 
early books were presumably printed without the help of 
a press, the impression being obtained by rubbing the 
back of the sheet while it was in contact with the thinly 
inked block. Only one side of tte paper was printed, 
the other being left blank. In later examples, however, 
both sides of the paper were printed on, and it is inter- 
esting to note that the ink penetrated sufficiently into 
the substance of the paper as to be distinctly seen through 
as the page lies open in its present situation. 

In Case L, which is devoted to these block books, the 
first example exhibited, the product of an unknown printer 
in the Netherlands, shows that an ink has been employed 
which was either brown in colour originally, or has faded 
to that hue. The more probable explanation is that the 
ink was made of an impure carbon, which would give a 
brown tint. In all the other examples in the same case 
the printing ink is of a full black, although instances 
are not wanting in which for lack of liberality on the part 
of the printer it does not present a complete opacity. 

These early works follow the old manuscript model in 
the possession of large ornamental initials, and other 
adornments which were afterwards added by the " rubri- 
cator." In one specimen we can note that the capital 



EAELY METHODS OF MANUFACTURE 135 

letter at the commencement of every sentence has an up- 
right stroke of red, which has as obviously been executed 
by hand as has been the rough colouring of some of the 
picture blocks. The specimen referred to is known as the 
42-line Bible, which is attributed to the press of Guten- 
berg at Mainz, about 1455. The red colour has apparently 
much deteriorated, and it would be interesting to know 
the nature of the pigment. In another example, the 36- 
line Bible, also from Mainz, the red initials show a full 
scarlet. 

German Books. In Case V., which is devoted to examples 
of early printing from Germany, we find the first illustrated 
edition of Virgil, 1502 A.D., with a preface in which the 
compiler boasts in Latin verse that by the help of the 
pictures the ignorant will be able to follow the text as 
well as the learned. The illustrations are certainly very 
good, with engraved lines of such fineness that they must 
have required an ink. of fair quality to do them justice. 
There is no trace of fading in any of these books, nor 
should we expect to find any. For carbon is imperishable 
except by the agency of fire, and, happily, as it is the most 
easily obtained and cheapest black pigment known, it was 
naturally adopted by the first printers. 

In some cases the ink is seen to have " set off " on th e 
opposite page, a fault from which modern books are by no 
means free, showing that the varnish used with the carbon 
was improperly prepared, or that an impure form of 
lamp-black was used. 

Italian Books. In Case VI., Italy, 1465-1472 A.D., we 
find specimens of printing which are very brown in tone. 
In one example, especially No. 7, there are two full-page 
line drawings (wood blocks), which appear as if printed in 
strong vandyke brown. The engravings on the hidden 
side of the leaves are seen through the paper so distinctly 
as to give the idea that the ink must have contained some 
corrosive principle that allowed it to eat into the fibres of 
the paper. 

Dutch Books. In Case IX., Netherlands, there is a 
specimen with brown ink which compares unfavourably 
with the brilliant black of the ink in other exhibits in 
close proximity to it. Another specimen shows the paper 



13(3 INKS AND- THEIR MANUFACTURE 

yellow and soiled, while the print is strong. In this 
example there are some marginal notes in a very much 
faded writing ink. It is quite possible that the brown 
tint observable in some of these old specimens of the 
printer's art is due to the use of carbon prepared from the 
soot of burning wood, or peat. Such a product has long 
been in use as a brown pigment by water-colour painters 
under the name of Bistre. 

EARLY METHODS OF MANUFACTURE. 

The old wall ink (atramentum tectorium] described by 
Pliny is the forerunner of our printing ink, which is essen- 
tially a kind of rapidly drying black paint. 

One of the earliest printed accounts we possess of the 
manufacture of printing ink is that given by the Venetian 
Canneparius * in his book on inks published in 1660. His 
ink consisted of i Ib. of a varnish of linseed oil and juniper 
gum thoroughly incorporated with i oz. of smoke-black, 
and boiled over a slow fire to the required- degree of 
consistency. 

According to the description given by Moxon in his 
Mechanick Exercises-^ in 1683, the printing ink then made 
in England was very inferior to the Dutch ink. The 
main differences were that in the latter only linseed oil 
and little rosin were used, that the oil was better prepared, 
and that the varnish was only incorporated with the black 
by the pressmen immediately before use ; whereas in the 
manufacture of the English ink much rosin (and fre- 
quently train oil) was added to the linseed oil, which was 
also insufficiently boiled, so that the ink was oily and 
separated in the paper. 

* De Atramenti?, p. 260. 

f ^Moxon's actual words are worth quoting, if only on account of their 
quaintness. " The providing of a good inck, or rather good varnish for 
inck, is none of the least incumbent cares upon our master-printer, 
though custom has almost made it so here in England ; for the process 
of making inck being as both laborious to the body, as noysom and 
ungrateful to the sence, and by several odd accidents dangerous of firing 
the place it is made in, our English master-printers do generally discharge 
themselves of that trouble ; and instead of having good inck, content 
themselves that they pay an inck maker for good inck, which may yet 
be better or worse according to the conscience of the inck maker." 



EARLY METHODS OF MANUFACTURE 137 

. Manufacture of Dutch Printing Ink Varnish. A caul- 
dron was half filled with old linseed oil, covered, and 
heated over a brisk fire until the oil boiled. When heated 
to a sufficient temperature the oil was fired several times, 
being each time extinguished by means of the cover until 
eventually a varnish of the required consistency was ob- 
tained, this point being determined by cooling a few drops 
on an oyster shell and testing it between the finger and 
thumb. It was then allowed to cool somewhat, and clarified 
by squeezing it in the hand through linen. 

When rosin was added, it was used in the proportion of 
J to i Ib. to each gallon of oil. Moxon asserted that the 
addition of too much rosin made the ink become yellow : 
but Savage denied this, since in his experience rosin thick- 
ened the oil, and prevented it separating from the ink and 
spreading through the paper.* 

Moxon stated that suitable varnish might be made 
without actually burning the oil ; but here again Savage's 
experience was that, although when linseed oil was boiled 
until viscous it yielded a clean and workable ink, yet after 
a few days the oil separated to some extent and spread 
through the paper. 

Savage considered that whilst Moxon's strictures on the 
English press work of the seventeenth century were justi- 
fiable, yet compared with the English ink of the early 
nineteenth century this boasted Dutch ink would have 
been regarded as worthless. 

Fertel's Method of Preparing Ink. Fertel, a French 
printer of St. Omers, published a work on pressmanship 
in 1723, in which he described the manufacture of 
printing ink.f 

This was prepared by heating linseed or nut oil in a pot 
with an adjustable cover until the vapours became inflam- 
mable (about 2\ hours), a crust of bread being introduced 
to "withdraw grease from the oil," and removed when 
carbonised. The oil was then withdrawn from the fire, 
the pot uncovered, and the vapours allowed to burn. The 
addition of turpentine oil advocated by some printers was 



* The Preparation of Printing Ink, 1823, p. 29. 

f La Science pratique de V Imprlmerle. St. Omers. 1723. 



138 INKS AND THEIR MANUFACTURE 

objected to by Fertel on the ground of making the ink 
clog the face of the type. 

The varnish thus prepared was incorporated with smoke- 
black from pitch resin collected in a chamber hung with 
sheep-skins, the usual proportions being 5 oz. to 2 Ibs. of 
varnish, and the ink ground thoroughly and worked upon 
the inking-table. In Savage's opinion this proportion of 
lamp-black was too small for a good ink. 

Breton's Method. In 1751 Breton,* printer to the 
King of France, published an account of a very similar 
method of preparing printing ink. For the manufacture 
of 100 Ibs. of varnish no to 112 Ibs. of nut oil were 
heated in a closed copper or iron vessel, which was usually 
pear-shaped, on a clear fire for about two hours. It was 
then removed and "burnt," the process being repeated 
several times. Finally, it was boiled over a slower fire for 
three hours until of the consistency of glue, when it was 
strained through linen. Turpentine oil and litharge were 
not recommended by Breton on the ground of their clogging 
the type. 

This " burnt oil " or varnish was thoroughly incorporated 
by the pressman on the inking-table, with lamp-black in 
the proportion of 2\ oz. to I Ib. 

Breton's recipe has become a standard one, and was 
copied into the books of different later writers, such as 
Lewis (1763), Papillon, &c. 

The method of boiling was substantially identical with 
the Dutch method described by Moxon. Savage endorses 
Breton's condemnation of the use of litharge in the pre- 
paration of the varnish. 

The sixth edition of the Encyclopaedia Britannica (1823) 
was apparently the first to publish any substantial differ- 
ence from these early methods in the manufacture of 
printing ink, the improvement being the addition of soap 
to the constituents, an addition which, though probably 
well known to certain manufacturers, had been kept as a 
trade secret. The effect of the soap was to cause the ink 
to leave a clean and sharp impression on the paper, to 
prevent the type from becoming clogged, and to prevent 
the ink from " skinning " when kept. 

* Encyclop&die Methodique. vol. v. p. 633. 



EAELY METHODS OF MANUFACTUKE 139 

In the Encyclopedia recipe the burnt oil was mixed 
whilst still warm with 2 Ibs. of black rosin and I Ib. 
of hard soap in slices. In Savages opinion this amount of 
soap is too much, and would be liable to make the ink 
daub the type and produce blurred impressions. 

Savage's Method of Manufacture. In 1823 Savage, 
who had studied the manufacture of printing ink from 
the point of view of the practical printer, published a 
book on the subject, in which he discussed all the previous 
methods of manufacture. 

For the preparation of the varnish he recommended the 
use of old linseed oil and black or amber rosin, which was 
melted into the oil at a temperature of not less than 
306 F., the approximate melting-point of the rosin. 

Six quarts of linseed oil were heated in a pot over a 
brisk fire, and the vapours tested with a light from time 
to time. When the flashes produced became stronger, 
the pot was removed, and the oil fired whilst kept con- 
tinually stirred with an iron ladle. The flame was extin- 
guished occasionally by placing the cover over the pot, so 
as to test the consistency. When, on cooling, it could be 
drawn into strings about half an inch in length, it was 
judged to be sufficiently burnt for book-work. 

Care was taken to prevent the oil frothing up through 
too violent heating, and thus running the risk of the 
entire mass bursting into uncontrollable flame. 

After cooling somewhat in the covered vessel the 
"burnt" oil was mixed with 6 Ibs. of rosin gradually 
stirred in, and then with if Ibs. of brown soap in thin 
slices, and was finally heated to the boiling-point. 

This varnish, whilst still warm, was next poured little 
by little into an earthenware vessel containing 5 oz. of 
Prussian blue or indigo, or a mixture of these, 4 Ibs. of 
mineral lamp-black, and 3^ Ibg. of vegetable black, and 
the whole stirred until free from lumps, and finally ground 
in a levigating mill. 

Modern Methods of Preparing Printers' Ink. 
Although the old method of preparing printers' or litho- 
graphic varnish, by heating the linseed oil until inflam- 
mable vapours are given off, and setting fire to these, is 
still in use, it has been found that the actual burning of 



140 INKS AND THEIR MANUFACTURE 

the oil is not an indispensable part of the process, and 
various other methods of thickening the oil and converting 
it into varnish are now employed. 

Other ingredients are also added to the linseed oil 
varnish in addition to the rosin and soap used in Savage's 
time, and this is especially the case with the cheaper 
kinds of inks such as are used for newspaper work. 
Various processes for preparing a black pigment to be 
used in place of lamp-black have also been described in 
patents taken out during the last thirty years. 



CHAPTER IX. 

MANUFACTURE OF VARNISH. 

CONTENTS. Boiled oils Burnt oil Varieties of lithographic 
varnish Andre's apparatus for boiling oil Apparatus with 
steam jacket and air blast Boiling with superheated steam 
Treatment with oxygen Linseed oil substitutes. 

Boiled Oils. The oils classified under the term "drying 
oils " are distinguished from other oils by the greater 
rapidity with which they form a solid varnish on exposure 
to the air at the ordinary temperature. Strictly speaking, 
this difference is one of degree rather than of kind, for it 
has been shown that even oils, such as olive and almond 
oils, do eventually dry after the lapse of a long time. 

The principal drying oils are linseed, walnut, hempseed, 
poppyseed, nigerseed, and the curious tung, or Chinese 
wood oil. For the characteristics and methods of examining 
these oils the reader is referred to works on the analysis 
of oils. Other oils, such as cotton-seed and maize oils, 
occupy an intermediate position between the "drying" 
and " non-drying" oils, and are usually known as "semi- 
drying" oils. The drying capacity of oils is usually attri- 
buted to the presence of a considerable amount of the liquid 
fatty acids, linolenic and isolinolenic acids, whilst another 
acid, linolic acid, probably contributes to the process. 

Fixed vegetable and animal oils consist in the main ot 
compounds of glycerin with saturated and unsaturated 
fatty acids, the latter predominating. Thus, olive oil con- 
sists principally of a compound of glycerin and oleic acid, 
G 18 H M 2 ; cotton-seed oil contains a large proportion of 
glycerides containing linolic acid, C 18 H 32 2 ; whilst linseed 
oil and other "drying" oils are characterised by the 
amount of the still more unsaturated linolenic and isolino- 
lenic acids, C 18 H 30 2 , they contain. 



142 INKS AND THEIR MANUFACTURE 

Each of these unsatu rated fatty acids and their glycerin 
compounds (glycerides) are capable of entering into com- 
bination with chlorine, bromine, or iodine, forming satu- 
rated compounds. Oleic acid, for instance, yields oleic 
dibromide, C 18 H 34 Br 2 2 ; linolic acid gives linolic tetra- 
bromide, C 18 H 32 Br 4 2 ; and linolrfnic acid, linolenic hexa- 
bromide, C^H^BrgOg. 

In like manner they are capable of being saturated with 
oxygen, and this is part of the change that occurs when a 
film of drying oil hardens into a varnish on exposure to the 
air, whilst the process can be considerably accelerated by 
subjecting the oil to a preliminary treatment known as 
"boiling.'' 

In this process, the exact nature of which still needs 
elucidation, considerable alteration of the "raw " oil takes 
place during the partial oxidation. Such boiled oils were 
at one time prepared solely by means of heat, but subse- 
quently various substances, known as " driers," were added 
to accelerate the oxidation, which was also promoted by 
injecting hot air into the hot liquid. 

Of the various " driers," which appear to act mainly as 
conveyors of oxygen from the air to the oil, salts of lead 
and manganese, in the proportion of a few pounds to the 
ton, have been found the most satisfactory, an,d are the 
most frequently used. 

The varnish used in the manufacture of printers' ink 
differs from the varnish used by painters and linoleum 
manufacturers in being prepared without the addition of 
any "driers" whatever. It is also as a rule much paler 
in colour. 

The apparatus used in the old method of boiling oil 
consists of a kettle, which is heated over a free fire (Fig. 30). 
Over this is suspended a lid, which can be lowered to close 
the vessel and immediately extinguish the flames when the 
evolved vapours take fire. To prevent frothing, the pan is 
only filled to half its capacity with oil. 

Burnt Oil. In preparing oil for the manufacture of 
printing ink, the process of oxidation is carried still 
further than in the process of boiling. In the old process 
of firing, as described in the preceding pages, the oil 
becomes very dark in colour, and apparently undergoes 



MANUFACTURE OF VARNISH 143 

considerable decomposition, probably attended with poly- 
merisation similar to that which occurs in the vulcanisation 
of oils by means of sulphur chloride. 




Fig. 30. Free-fired pan for boiling oil. 

The amount of free acid liberated in the oil during the 
process is much greater than in the case of oil that has 



144 INKS AND THEIR MANUFACTURE 

been boiled for a very long time at a temperature of 260 
to 300 C. 

Printers' varnish thus prepared has good drying proper- 
ties, and is considerably denser than the raw oil (vide infra). 

Leeds* gives the following details of the modern method 
of boiling oil for lithographic varnish : The kettle is filled 
to about two-thirds of its capacity with linseed oil that has 
been kept in store for some time. As soon as the water 
has been expelled and the froth of albuminous impurities 
skimmed off, the temperature is raised to about 500 5 60 P., 
and the boiling continued until the required degree of 
consistency is attained, after which the varnish is left to 
cool and settle and decanted into storage tanks. 

The time required depends upon the temperature of 
boiling and on the maturity of the raw linseed oil. A high 
temperature accelerates the conversion, but has the draw- 
back of producing a darker product. 

Leeds lays ^considerable stress on the importance of using 
a well-matured oil. Crude linseed oil immediately after 
expression contains impurities which separate out to a 
greater or less extent on standing for a few months. If 
such crude oil be used for boiling there is much more froth 
and a poorer yield of a darker varnish, whilst the time and 
consumption of fuel are greater. 

The ordinary loss ranges from about 3 to 10 per cent., 
according to the maturity of the oil. 

It is interesting to note that the importance of using an 
old oil in the preparation of the varnish was recognised by 
all the older writers from Moxon to Savage. 

Varieties of Lithographic Varnish. Five or six 
varieties of lithographic varnish are in use, ranging in con- 
sistenc} 7 from a very thin product to one of extreme vis- 
cosity. These are termed "extra strong," "strong," 
"middle," "thin," "tint," and "thin tint," according to 
their degree of viscosity. Leeds (loc. cit.) t who has 
thoroughly studied the chemical changes that take place 
in the conversion of the raw oil through the various inter- 
mediate changes into " extra strong " varnish, points out 
that the most viscous products have less drying capacity 
than the thinner varnishes, and that their viscosity, which 
* Journ. Soc. Cliem. Ind., 1894, xiii. 203. 



MANUFACTURE OF VARNISH 



145 



gives them greater carrying power as a medium for pig- 
ments, is their chief recommendation. 

The following table, abridged from that of Leeds, repre- 
sents some of the changes undergone by raw linseed oil in 
this process of boiling, and in the old method of igniting 
the vapours to produce "burnt" oil. 



Varnish. 


Specific 
gravity 


Free 
acids as 


Saponifi- 
cation 


Iodine 


Uusaponi- 
fiable 




at 15.5 C. 


oleic acid. 


value. 




matter 






Per ceiit. 






Per cent. 


'Tint" 


0.9584 


1.46 


J97- 5 


II3.2 





'Thin" 


0.9661 


1.76 


196.9 


IOO.O 


0.62 


'Middle" . 


0.9721 


1.71 


197-5 


91.6 


0.85 


' Strong " . 


0.9741 


2.16 


190,9 


86.7 


0.79 


' Extra strong " 


0.9780 


2.51 


IS8.9 


83.5 


0.91 


' Burnt " thin 


0.9675 


6-93 


195-5 


92.7 


'.35 



Andres' Apparatus for Boiling Oil. This (Fig. 31) 
consists of a cylindrical copper kettle, A, to the middle of 
which is attached the 
collar D, which sup- 
ports it in the furnace. 
The top of the vessel 
is bound by a strong 
iron ring, to which are 
attached the chain and 
tackle (?, thus enabling 
the vessel to be rapidly 
withdrawn from the 
fire by means of a 
crane. The lid, B, fits 
closely to the upper 
ring, forming a nearly 
air-tight joint, so that 
flames can be imme- 
diately extinguished. 
Above the furnace is 
fixed a hood provided 
with a flue to conduct 

away the vapours. Fig. 31. Andres' apparatus. 

K 




146 INKS AND THEIR MANUFACTURE 

It was asserted by Savage, and accepted for long after- 
wards, that actual ignition of the vapours from the oil was 
essential for the production of a varnish suitable for 
printing ink. It is now known, however, that the same 
result can be obtained by boiling the oil at a higher tem- 
perature- than in the preparation of ordinary boiled oil for 
paints. 

Apparatus with Steam Jacket and Air Blast. A 
pair of steam-heated kettles, each of which takes a 
charge of about 350 kilos., is shown in Fig. 32. These 
are constructed with jackets capable of resisting a pres- 
sure of several atmospheres. The oil is heated by steam 




Fig. 32. Steam-heated kettles. 

at about 130 C. or more, under a pressure of four to five 
atmospheres, whilst air is blown through until the var- 
nish is of the required consistency. Each kettle is 
covered with a dome-shaped cover, in which is an outlet 
pipe for the escape of the vapours evolved. The steam 
enters the jacket of the pan b at c', and passes through 
e into the jacket of the pan a. At f is a cock for blowing 
off, which is so regulated that only a little steam 
escapes, whilst the condensed water is drawn off through 
the tap at g. 

Frederking's apparatus for boiling oil contains a steam 
coil, round which has been cast the molten metal form- 
ing the pan. Steam under any required pressure is 
passed through the coil, and the contents of the kettle 



MANUFACTURE OF VARNISH 



147 



readily raised to temperatures of 350 to 400 C. without 
danger, the pressure being solely on the piping and not on 
the metal pan itself. 

An apparatus described 
by Andds * contains a cir- 
cular iron pipe supported 
on the bottom of the vessel, 
and connected with bellows 
by means of a vertical tube. 
Air is blown into the oil 
through small holes about 
0.5 c.m. in diameter in the 
circular pipe, and the 
heated oil kept in motion 
during the thickening pro- 
cess. When- cold air is 
blown into the oil the 
temperature is kept below 
270 C. to prevent the 
varnish being too dark in 
colour. 

Sauer's Apparatus. 
This consists of a heating 
vessel in which a paddle 
agitator is made to revolve 
round a central shaft, 
whilst a current of hot air 
enters near the bottom of 
the apparatus. 

Fig. 33 shows another 
apparatus for preparing fljr 1 

varnish by this method. fl^Ttl] 

The air is driven by means 
of the pump A, through 
the coil B, and is heated 
to the required temperature 
before entering the oil in 
the vessel C, through the 
small openings in the pipe. 

The varnish produced by this method dries well, but is 
* Drying Oils, 1901, p. 237. 




148 INKS AND THEIK MANUFACTUKE 

usually somewhat darker than that produced by the ordi- 
nary method, especially if the temperature be allowed to 
rise too high. 

Boiling with Super-heated Steam. Apparatus in 
common use for this purpose consists of a kettle con- 
taining- a coil through which passes steam heated to a 
temperature of about 400 0. by being passed through a 
super-heater kept outside the chamber. The kettle is 
provided with a cover which can be easily removed by 
means of a chain and tackle, whilst an exit pipe in this 
cover conducts the escaping vapours to the bottom of the 
super-heater, whence they are drawn up into the fire and 
consumed. Hence the process is accompanied by little or 
no smell. 

Lithographic varnish thus prepared has the drawback 
of being darker in colour than ordinary " boiled " varnish, 
but, on the other hand, the process is much more rapid. 

Treatment with Oxygen. Very pale varnishes are 
obtained by subjecting linseed oil, heated to a moderate 
temperature, to the action of oxygen. Instead of losing 
in weight as in the ordinary boiling processes, the var- 
nish shows an increase of about 4 per cent, through the 
addition of the oxygen. 

Leeds (loc. cit.) found that varnishes thus prepared were 
free from the brownish-green fluorescence of ordinary 
lithographic varnishes, but that they possessed a much 
more unpleasant odour. 

In a process protected by " Erin's Oxygen Co." (Eng. 
Pats., No. 12,652, 1886; and No. 18,628, 1889) a current 
of pure (90-93 per cent.) oxygen is passed into the space 
above the oil, instead of being blown through it. The 
apparatus used for the purpose consists of a closed 
steam -jacketed pan, in which the oil is kept in motion 
by a revolving agitator. The oxygen is introduced 
when the oil has been heated to nearly 100 C., and is 
absorbed, at first slowly, and eventually more rapidly than 
it is supplied. So much heat is produced by the 
reaction that it is ultimately necessary to cool the jacket 
by admitting water into it. 

Linseed oil varnish prepared by treatment with oxygen 
differs from the original much more than varnish prepared 



MANUFACTUKE OF VAKNISH 



149 



by boiling. Thus it contains about ten times as much free 
acid, and has a considerably higher specific gravity, whilst 
its absorption capacity for iodine is much lower. 

Leeds (loc. cit.) gives the following results obtained 
in the analysis of two samples of these oxidised linseed 
oils. 



Varnish. 


Specific 
gravity 
at 15 C. 


Free 
acids as 
oleic acid. 


Saponifi- 
cation 
value. 


Iodine 
value. 


Unsaponi- 
fiable 
matter. 


Oxidised oil, \ 
weak . / 


1.03 


Per cent. 
1828-4 


221 


58.8 


Ter cent. 
0.87 


Oxidised oil, \ 
strong . / 


1.05 


18.528.9 


223.5 


53-5 


0.97 



Treatment with Ozone. It was shown some years ago 
by Schrader and Dumcke that a varnish was rapidly pro- 
duced by the action of ozone upon raw linseed oil, which 
was also bleached in the process. 

Apparatus for the purpose was subsequently patented 
in Germany by Graf and Co. , a current of ozone from any 
suitable generator being conducted through the heated 
oil. Care is needed in this operation to prevent the oxida- 
tion proceeding too far, so that a semi-solid caoutchouc- 
like mass is obtained. In fact, patents for preparing 
commercial rubber substitutes by the action of ozone 
under pressure upon linseed and other oils have been 
taken out by Rosenblum and Rideal (Eng. Pats. , No. 95 29, 
1897 ; and No. 6464, 1898). 

Ramage (Eng. Pat., No. 7242, 1901) has devised a pro- 
cess for making varnish of good drying capacity by heat- 
ing non-drying oils with ozone in the presence of an 
oxygen-occluding substance such as platinised asbestos. 

Milthel and Lufke's Electric Process. In this process, 
patented in Germany (Ger. Pat., No. 29,961), the oil is 
treated with a mixture of gases (e.g., oxygen with steam, 
or nitrous oxide with air or oxygen) which has been sub- 
jected to the action of a powerful electric discharge whilst 
passing through a series of condensers. The oil is heated 



150 INKS AND THEIR MANUFACTURE 

by means of a steam coil, whilst the gaseous mixture 
enters through holes in a small spiral in the bottom of the 
tank. The volatile products of the reaction and the un- 
used gas are drawn off by a pump at the top. 

Linseed Oil Substitutes. Numerous substances have 
been proposed as substitutes for linseed and other drying 
oils. An ink containing none of the ordinary oil varnish 
was described by Savage in 1823 (Joe. cit.) } and methods 
of preparing other varnishes of the same kind can be 
found by reference to the patent list at the end of this 
book. One of the most interesting of these is a natural 
drying mineral oil, which is found in Java and known 
commercially as Grisel oil. The use of this is claimed by 
Stoop (Eng. Pats. No. 24,504, 1897 5 2 3 ) 7 I 5 1898). 



CHAPTER IX. 

PREPARATION AND INCORPORATION OF THE PIGMENT. 

CONTENTS. Black for printing ink Modern apparatus 
Thenius' lamp-black furnace Furnace for producing black 
from pitch Other black pigments Carbon blacks Purifica- 
tion of lamp-black Composition of lamp-blacks Methods 
of examining lamp-blacks and gas-blacks Mixing 
the black and varnish Mixing the varnish and lamp-black 
Quack's mixing machine Werner and Pfleiderer's mixing 
machine Lehmann's mixing machine Grinding Leh- 
rnann's grinding machines Machines by Neal, Jackson, King- 
don Lithographic printing ink Collotype ink. 

Black for Printing Ink. The nature and degree of 
purity of the black pigment incorporated with the varnish 
is of the highest importance, especially in the case of ink 
intended for fine-art printing, since the depth and per- 
manency of the tone largely depend on this. Hence many 
printing ink manufacturers prepare their own lamp-black 
so as to have the entire manufacture under their control, 
and to be able to produce an absolutely uniform product. 
Some of the older methods and apparatus used in the 
preparation of lamp-black have already been described in 
chap, i., and here it is only necessary to describe some of 
the more modern apparatus. 

Fig. 34 represents a modern apparatus used for the 
production of lamp-black from oil, and is a development 
of the ancient method. The supply of oil is regulated by 
the small chamber outside, whilst the air enters through 
holes beneath the lamp. The smoke from the lamp is 
conducted through the chimney into a chamber, where ib 
is deposited and collected. 

Another apparatus intended for the rapid production of 
a coarser lamp-black is shown in Fig. 35. It consists of a 
revolving cylinder, through the interior of which passes a 



152 INKS AND THEIR MANUFACTURE 

current of cold water. A series of lamps are kept burn- 
ing below this, and the smoke deposited on the cylinder 

is removed by means of the 
brush. 

Thenius' Lamp - black 
Furnace. This apparatus, 
devised by Thenius for the 
collection of lamp - black 
from coal-tar oil, consists of 
a series of iron chambers 
opening into one another. 
In the first of these the oil, 
freed from naphthalene as 
far as possible, falls drop by 
drop from a tank above on 
to a red-hot plate, over which 
passes a limited supply of 
air. The smoke is carried 
through the series of cham- 
bers, forming black deposits 
of different grades of fine- 
ness on the walls. About 
70 kilos, of smoke-black are 
obtained, from 400 kilos, of 
Fig. 34. Lamp-black apparatus. the oil, about half of it 

being of very fine quality. 

Furnace for producing Black from Pitch, Rosin, &c. 
An apparatus used in Germany consists of a chamber 
with a slanting outlet tube for the smoke leading to the 
chamber where it is deposited, and a movable iron cover 
with a regulator for the air supply. The combustible 
material is placed in a pan at the bottom of the chamber, 
whilst the exterior of the pan is cooled in another tray 
containing water, the object of this being to prevent the 
temperature rising too high and causing dry distillation 
to take place. 

In a recent United States patent (No. 741,726, 1903) 
tar is heated to about 300 400 C. in a rotating cylindrical 
furnace, in which is a spiral ridge to conduct the tarry 
matter towards the outlet at one end, whilst the volatile 
products escape through a special opening. 




PIGMENT 153 

Other Black Pigments. Numerous substitutes have 
been proposed for lamp-black as a pigment in printing ink, 
but not many of these have come into general use. 

Frankfort Hack or drop Hack was originally prepared 
by heating vine twigs in closed crucibles, extracting the 
residue with water, drying the powder, mixing it with a 
weak solution of glue, and forming it into pear-shaped 
drops. Other substances, such as bone shavings, &c., are 
now used in its manufacture. 




Fig. 35. Lamp-black apparatus. 

This and other forms of charcoal have a granular cha- 
racter, whereas lamp-black is flocculent, and as no amount 
of grinding will effect thorough incorporation of such 
granular pigments with the varnish, they are unsuitable 
for good printing ink. The same remark applies to 
various shale and mineral blacks. 

Carbon Blacks. The black pigment obtained by 
the deposition of the smoke from burning gas upon 
metallic surfaces is sold under various trade names, such 
as gas Mack, peerless black, hydrocarbon black, silicate of 
carbon, jet black, &c. 



154 INKS AND THEIE MANUFACTURE 

It was prepared on a small scale by certain manufac- 
turers in this country from the ordinary gas supply of 
towns some forty years ago, but owing to its high price 
(5s. a pound) never came into general use. 

The discovery of natural gas in different parts of the 
United States put a cheap source of gas carbon at the 
manufacturers' disposal. Cabot * states that the first 
experiments with the natural gas were made in 1872 in 
Pennsylvania, and a factory was built to manufacture the 
pigment on a commercial scale. The first lot was sold at 
about I os. a pound, and the demand soon exceeded the 
supply. Other factories were established and the price 
rapidly fell, until in 1889 it was as low as i^d., and several 
firms were ruined. Since then it has again risen some- 
what in price, and now fetches about 3^. or 4^. a pound, 
which is dearer than the price of black prepared from the 
smoke of heavy oils. 

The gas issues from borings about 2000 feet in depth 
by 8 inches in diameter, and is burned in ordinary 
gas jets. In the earliest method of collecting the black 
flat-bottomed cast-iron pans were fixed above the jete, and 
the soot removed by means of travelling scrapers. Several 
United States patents were next taken out for processes 
in which the flame was made to impinge on revolving iron 
cylinders. In 1883 claim was made for a process in 
which a large plate with holes for ventilation was made 
to revolve over the burners, and the black removed by 
passing over a fixed scraper. 

The method now in general use was introduced in 1884 
by Mood, who employed revolving iron rings 3 feet in 
external diameter and 2 feet in internal diameter as the 
surface for the deposit. These rings were placed in six 
rows of fourteen each, and were enclosed in sheds to guard 
against air draughts. 

In another process, also commercially successful, the 
deposition surface is kept stationary, whilst the gas jets 
and collecting box revolve beneath it. 

The best yields obtained by these processes are about 
one pound of black for each 1000 cubic feet of gas 

* Journ. Soc. Chem. Ind., 1894, xiii. 128. 



PIGMENT 155 

consumed, but in some cases the consumption of gas is 
six or eight times as much. 

Carbon blacks are characterised by their intensity of 
tone, and the printing done with inks containing them 
has a rich glossy appearance. Owing to their being of a 
more granular character than lamp-black they are not so 
readily incorporated with the varnish, and were not looked 
upon with favour by English printers long after they had 
been extensively used in America. English manufacturers 
have now introduced rollers of chilled steel in place of 
granite for the grinding of carbon black inks, and their 
products can compete with those of American origin.* 

Gas-black consists mainly of carbon, and has only traces 
of mineral matter. Samples analysed by Cabot (loc. cit.) 
contained 92 to 93 per cent, of carbon, 5 to 6 per cent, of 
oxygen, and I to 2 per cent, of hydrogen. 

Like lamp-black, impure gas-black is always contami- 
nated with tarry oils, which can be removed by calcination 
(p. 156), leaving a residue containing 98 to 99 per cent, of 
carbon. Its tinctorial power is considerably higher than that 
of lamp-black, and it will impart a deep grey tone to 100 times 
its weight of white lead. It requires approximately twice as 
much varnish as lamp-black does to form an ink of the 
right consistency, and the ink thus dries more slowly. 

Owing to its hygroscopic character, carbon-black must 
be stored in well-closed vessels, otherwise the water it 
absorbs forms globules with the oil, and interferes with 
the perfect incorporation. 

Carbon-blacks are miscible with water, and this property 
affords a means of distinguishing them from lamp-black. 

Purification of Lamp-black. However carefully pre- 
pared, lamp-black, even after careful grading, has a more 
or less brownish tint, due to the presence of volatile, tarry, 
and oily matters derived from dry distillation of part of 
the organic substance used in the combustion. When 
these are eliminated, the residue consists of almost pure 
carbon, and is then deep black in tone. 

Chemical Purification. The technical method of remov- 
ing the brown impurities is to boil the black with successive 

* Harding, Process Year JBook, 1898, p. 65 ; 1902, p. 126. 



156 INKS AND THEIR MANUFACTURE 

portions of strong caustic soda ley until only a faint colour 
is imparted on treating the substance with a new portion. 
The powder is then washed thoroughly and appears deep 
black to the eye. 

In* order to remove all traces of impurities, however, it 
is necessary to continue the boiling with caustic soda 
until a colourless extract is obtained, and subsequently to 
boil the residue with aqua regia until nothing more dis- 
solves. The final product, after washing with water, is a 
deep black, very friable powder. It is practically pure 
carbon, and emits no smell when burnt. The cost of 
handling the material so many times is too great to permit 
of chemical purification being used in the preparation of 
any but the very finest and most expensive grades of lamp- 
black (Andts). 

Purification by Calcining. The brown tarry oils and 
other impurities in lamp-black can be expelled by heating 
the crude product to a sufficient temperature to volatilise 
them. In this process it is essential to prevent any air 
coming into contact with the hot carbon, which in that case 
would be partially burned into oxides of carbon; and also 
to avoid overheating, the result of which is to cause the 
lamp-black to cake into lumps, which are very difficult to 
distribute uniformly through the lithographic varnish. 

The apparatus used for the calcination is a cast-iron box, 
in the cover of which a small opening is left to allow the 
volatile impurities to escape. The outside of this box is 
coated with a thick layer of clay to protect the metal from 
oxidation, and the juncture of the cover carefully luted 
with the same material. Every precaution is taken to avoid 
the slightest opening into the box, with the exception of 
the small one in the cover. 

After being charged with the crude lamp-black, the box 
is placed in a suitable furnace and heated gradually from 
behind until the whole has attained a bright red heat. It 
is kept at this temperature for about thirty minutes, and 
then removed from the furnace and cooled in a current of 
air, the opening in the cover being protected from the pos- 
sible admission of atmospheric oxygen by having a piece 
of glowing charcoal placed over it. The box is not opened 
until quite cold, lest any oxidation of the carbon might 



PIGMENT 



157 



take place. To obtain an absolutely black product, it is 
often necessary to repeat the calcining as many as six times 
or more. According to Irvine the loss in weight on cal- 
cining lamp-black is upwards of 15 per cent. 

Composition of Lamp-blacks. After careful purifica- 
tion lamp-blacks consist of 96 to 98 per cent, of carbon, 
and contain very little mineral or oily products. 

The following analyses of four pure samples of lamp- 
black were made by Stillwell and Gladding*: 





i. 


2. 


3- 


4- 




Per cent. 


Per cent. 


Per cent. 


Per cent. 


Carbon .... 


97.38 


97-38 


96.24 


96.13 


Mineral matter (ash) . 


0.05 


0.05 


0.03 


0.23 


Moisture (loss at 100 C.) . 
Volatile substances 


0.07 
2.50 


0.08 
2.50 


0.03 
3-70 


0.04 
3.60 



A commercial sample of impure lamp-black recently 
examined by us gave the following results : Ash, 0.29 ; 
oily matter (ether extract), 8.12 ; and total nitrogen, 0.76 
per cent. 

METHODS OF EXAMINING LAMP-BLACKS AND GAS-BLACKS. 

In judging of the suitability of a black for printing ink, 
the main points to be taken into consideration are the 
intensity and permanency of its blackness, its tinctorial 
power, the fineness of its particles, and its freedom from 
any considerable proportion of oily impurities and mineral 
matter. 

Determination of Mineral Matter. A weighed quantity 
(about 0.3 grm.) of the powder is ignited in a weighed 
platinum basin over a small Argand flame, and the residue 
weighed when burned completely white. The best qualities 
of lamp-black contain only traces of ash (cf. "Analyses" 
supra). 

Tarry Oils. It has been pointed out by Irvine f that 
the halo to be observed round the letters in some old books 

* Process Year Book, 1901, p. 141. 

f Journ. tioc. Chem. Ind., 1894, xiii. 131. 



158 . INKS AND THEIR MANUFACTURE 

and papers is to be attributed to the presence of tarry 
compounds, such as pyrene and chrysene, in the black. 

For the determination of such impurities, 2 or 3 grms. 
of the sample are extracted with ether, the extract evapo- 
rated, and the residue weighed. A specimen of lamp-black 
examined by us in this way yielded 8. 12 per cent, of a dark 
yellow viscid oil, with a strong empyreumatic odour and a 
bitter taste. Smith * advocates the following qualitative 
test : A pinch of the powder is put on a piece of filter 
paper and moistened with a few drops of sulphuric ether, 
which will dissolve any oil present and then leave a brown 
or yellow stain surrounding the powder. 

Alkalinity or Acidity. Free alkali or acid, which may 
be left by the process of purification, may react with other 
constituents of the ink and lead to loss of colour. 

Free alkali is detected by boiling o.i grm. of the black 
with 10 c.c. of water, filtering, and adding a drop of phenol- 
phthalein solution to the filtrate (pink colour). If, on the 
other hand, the aqueous extract is acid, it will remain 
colourless on the addition of the phenol-phthalein, and 
will require the addition of alkali solution to produce the 
pink colour. 

Degree of Fineness. Lamp-black consists of foliated 
particles, while gas-black is finely granular in character, 
and vegetable charcoals (Frankfort black, &c.) still more 
granular. A practical test for comparing an unknown 
sample with one of known fineness is to mix equal weights 
of the powders with equal quantities of varnish, and to 
spread the mixtures in thin layers on glass. When the 
glass is held to a strong light, the layer of fine black will 
be found impervious to the light, whilst the particles of 
the coarse black allow the light to pass. 

Intensity. The above method of testing the fineness of 
the particles is also frequently employed for comparing the 
intensity of the tone of two samples ; but Smith (loc. cit.) 
objects to it on the ground that in the case of shale-blacks 
the oil varnish may rise to the surface, and the layer thus 
appear to be blacker than it really is. He therefore advo- 
cates making the comparative tests on wood instead of 
glass, under parallel conditions. 

* -Process Year Boolt, 1903, p. 137. 



PIGMENT 159 

Permanency. Apart from the results obtained in actual 
practice which obviously take time, Smith recommends 
testing the blacks with sulphuric acid and with solutions 
of sodium hydroxide and ammonia. Effervescence with 
the acid indicates the presence of carbonate, whilst if the 
blackness is at all fugitive, the pigment, when dried after 
treatment with alkali, may show a loss in intensity. 

Tinctorial Poiver. A paste is prepared by adding lin- 
seed oil to a mixture of o. I grm. of the black with 8 
grins, of white lead, and after thorough incorporation 
spread upon glass, and the tint compared with that given 
by a standard sample of lamp-black under the same 
conditions. 

Opacity Test for Covering Power. A mixture of o.i 
grm. of the powder, and i c.c. of oil is spread in a 
uniform layer over paper until the surface below becomes 
visible, the areas of paper covered by equal weights of two 
pigments thus affording a measure of their relative 
opacity. In some cases an additional amount of oil must 
be added to the mixture to enable it to be spread out to 
its maximum extent, so that the total amount of oil used 
may also be taken as a measure of the covering power. 

Distinction between Lamp-blacks and Gas-blacks. Cabot 
(loc. cit.) has based a distinguishing test on the fact that 
gas-black can be readily mixed with water (p. 155). ? 

MIXING THE BLACK AND VARNISH. 

Proportion of Black to Varnish. This will obviously 
depend to a large extent on the character of the printing 
for which the ink is required, as well as on the quality and 
nature of the pigment used. Thus for newspaper work a 
very different kind of ink is required than in the case of 
fine book work and illustrations. 

According to Andes* the proportion of lamp-black or 
other black in German printing ink ranges from about 
20 to 40 per cent., a little blue pigment (indigo, aniline 
dye-stuffs, &c.) being added to the best qualities of ink. 

He gives the following proportions as typical of inks in 
common use: 

* Oel und Buchdrucltfarben, 1889, p. 236. 



160 INKS AND THEIR MANUFACTURE 





Ink for 


Common 









Rotary 


Newspaper 


Book Ink. 


Ink for Illustrations. 




Machines. 


Ink. 








Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


Oil Varnish 


70-72 


7 6- 7 8 


77-79 


78 


78 


Lamp-black 


30-28 


24-22 


23-21 


20 


19 


Paris Blue . 









2 


2 


Indigo 














I 



Mixing the Varnish and Lamp-black. In some of 
the old foreign methods of mixing the pigment with the 
oil varnish, the ink was only incorporated by the pressman 
on the inking-stone immediately before use (see p. 1 36). 
As a thorough admixture of the ink was a tedious process 
the old English ink manufacturers were in the habit of 
preparing a complete product, though, according to Moxon 
(loc. cit.), the results given by this ink were inferior to the 




Fig. 36. Quack's Mixing Machine. 

Dutch printing. The mixing of the ingredients was 
effected by stirring them together in a vessel, and even- 
tually grinding them on a stone with a muller. Owing to 
the very light and dusty nature of the lamp-black, the 



PIGMENT 



161 



incorporation is now usually effected in a mixing machine, 
several types of which are in use. 

Quack's Mixing Machine. This is a simple and effective 
apparatus, consisting of a closed vertical cylinder with 
rounded bottom, in which revolve two interlapping flat 
rings, which scrape the sides of the vessel and effect a 
thorough admixture of the contents. The cylinder is 
supported outside by axles, so that it can be easily in- 
verted to remove the ink. 




- 37- Lehmann's Mixing Machine. 



Fig. 36 shows the mixing apparatus viewed from above. 

Werner and Pjieiderer's Mixing Machine. These are 
made in various sizes to lake charges of \ to 1400 kilos. 
They are constructed in the form of a horizontal cylinder, 
mounted on axles so as to be readily emptied, and the 
incorporation of the varnish and lamp-black is effected by 
means of revolving paddles. 

Lehmann's Mixing Machine. Fig. 37 represents the 
mixing machine supplied by Messrs. Keller and Co. for 
mixing lamp-black with oil. It is made in two sizes to 



162 INKS AND THEIR MANUFACTURE 

take charges of twenty-two and sixty-six gallons, and the 
rotating blades are driven by 0.2 and 0.5 horse-power 
respectively. The machine is shown here in a tilted 
position for the discharge of ink, but when in action the 
opening of the vessel is horizontal, and is closed so as to be 
completely dust proof. A special lamp-black cylinder is 
attached to the cover of the machine, and the black falls 
from this through a sliding shutter into the mixing 
chamber. 

GRINDING. 

After thorough admixture in a mixing machine as 
described in the preceding pages, the pulp of printing 
ink requires grinding between rollers, so as to reduce it to 
an absolutely homogeneous mixture free from all lumps. 
For this purpose it is transferred from the mixer to a mill, 
' in which it is passed between rollers of fine-grained hard 
stone such as porphyry, one grinding in a mill with six or 
nine rollers being usually sufficient if the material has 
been properly mixed. 

For grinding granular pigment such as gas-black, 
machines with rollers of chilled steel are used in America 
and more recently in England. 

Lelimanrts Grinding Machines. These machines have 
been extensively supplied by Messrs. Keller and Co. to 
printing ink manufacturers. They are constructed in 
different sizes and with three hard metal rollers of chilled 
steel or of porphyry. A mill suitable for smaller manu- 
facturers is shown in Fig. 38. This is 40 inches in length, 
47 inches wide and 45 inches high, and has rollers 8 
inches in diameter. These rollers are composed of por- 
phyry, and have a surface harder than steel, so that the 
material is ground as finely as possible. They are made 
to run at different speeds, whilst the front roller has also 
an oscillating movement, both of which help to make the 
grinding more thorough. 

Further advantages claimed for this type of mill is that 
there is no possibility of the material overflowing from 
the sides, and that the rollers keep completely cool during 
the grinding, thus preventing any alteration in the colour 



PIGMENT 



163 



of delicate pigments, as sometimes occurs when grinding 
rollers become hot. 

The mill shown in the figure is capable of a daily output 
of 1 70 Ibs. of letterpress ink or 70 Ibs. of litho ink, and is 
driven by an engine of 0.8 horse-power. Larger mills 




Fig. 38. Lehmann's Grinding Mill. 

constructed by the same firm require 2.5 horse-power, 
and yield a daily output of 4 owt. of letterpress ink or 
130 Ibs. of litho ink, whilst still larger machines have 
six and nine rollers, and give twice and three times the 
output. 

Combined mixing machines (Fig. 37) and grinding 
machines are also employed by ink manufacturers. 



164 INKS AND THEIE MANUFACTURE 

In NeaVs grinding mill (Eng. Pat., No. 2640, 1860) the 
bottom roller alone revolves, whilst the top one is fixed. 

A grinding mill patented by Jackson (Eng. Pat., No. 957, 
1870) contains flat circular grinding plates which revolve 
on a vertical spindle. On the surface of these plates are 
teeth, whose cutting faces are arranged half in one direc- 
tion and half in the other, so that by reversing the motion 
from time to time half of the teeth are sharpened, whilst 
the others are in action. The plates are kept cool by 
means of air-chambers between the fixed and revolving 
discs. 

In a machine protected by Kingdon (Eng. Pat., No. 3598, 
1873) the rollers were made to revolve in opposite direc- 
tions, and the upper roller was much smaller than the 
lower. This arrangement was intended to accelerate the 
passage of the ink and prevent the darkening that some- 
times occurs in grinding coloured inks. 

Lithographic Ink. Printing ink for lithography is 
supplied in tins, the price ranging from 2s. to 405. per Ib. 
A fair quality of black ink can be obtained for about 5s. 
per Ib., and it does not deteriorate by keeping. It is in 
the form of a solid of the consistency of cold wax, and 
must be thinned down with varnish before it can be used 
for printing. A small quantity of ink is treated at a 
time, the varnish being added to it in minute quantities 
and rubbed down with the palette-knife. The ink is at 
first difficult to mix with the varnish, but when a little has 
been incorporated with it it will readily absorb more. A 
good deal of practice is necessary before the lithographic 
printer can master the initial difficulties of reducing the 
ink to a printable condition. He must be guided to a great 
extent in dilution of the ink by the state of the atmosphere 
and the temperature. 

The lithographer in a small way of business is frequently 
called upon to print such small things as concert pro- 
grammes and the like in fancy colours, and must know how 
to compound inks of different hues. By the aid of a stone, 
ruuller, palette-knife, and varnish he should find no diffi- 
culty in accomplishing the work. The pigment or pig- 
ments employed are rubbed down in small quantities with 
the palette-knife and with medium or thin varnish, or with 



PIGMENT 165 

a mixture of the two, according to the state of the ther- 
mometer. He then grinds the mixture with the muller, 
gathering it up again with the knife and regrinding again 
and again. More colour is added as the operation proceeds, 
and as the ink gradually gains in thickness it will become 
necessary to do this by scattering the pigment over the 
stone, and grinding down with the muller without the 
intervention of the palette-knife. But the latter must be 
employed to scrape the colour from the stone, pile it. up 
before submitting it again to the action of the mulier. 
Ink thus prepared works better if kept for a day or two 
before being used. 

For delicate tints, as in painting with opaque pigments, 
it is necessary to incorporate with the colour a considerable 
body of white, and for this purpose there is nothing better 
than zinc oxide. It is true that white-lead has more 
covering power, but there is considerable risk of chemical 
change occurring when it is mixed with certain other 
pigments. A transparent alumina introduced by Messrs. 
Madderton and Co. affords an excellent means (in conjunc- 
tion with oil) of rendering a coloured ink paler without 
changing its consistency. In chromolithography an ink is 
sometimes employed for a pale tint, or for enriching a 
colour already printed, in the same way that a water-colour 
is used by a painter ; that is to say, the ink is sufficiently 
thinned down by varnish to make the paper show through 
it. This device has the advantage of reducing the number 
of separate printings and so saving expense. It is not 
applicable to printing from type. It is almost unneces- 
sary to state that in printing establishments where a large 
amount of colour work is done, the inks are ground in 
mills, or are supplied ready compounded. 

Collotype Ink. The usual practice of the collotypist is 
to rub down lithographic chalk ink with " middle " varnish, 
turpentine, and olive oil, and when he requires inks of dif- 
ferent colours, he mixes each severally with a little 
turpentine before incorporation with the other media. It 
is also customary to add to black inks a small proportion 
of Prussian blue, indigo, or Venetian red to improve the 
tone. A special inking slab and muller are used for each 
colour. 



166 INKS AND THEIR MANUFACTURE 

Scknauss * gives definite directions for preparing ink for 
collotype work on these lines. From our own experiments 
we can affirm that much depends in the collotype process 
upon the thorough incorporation of the ingredients of the 
ink, upon its even distribution, and upon the degree of 
moisture in the atmosphere, which has an influence upon 
the gelatine surface. 

* Collotype, p. 56. 



CHAPTER XI. 

COLOUKED PRINTING INKS. 

CONTENTS. Early methods Manufactured inks Painters' 
pigments Early ignorance as to proper pigments Half-tone 
process block Necessity for cleanliness Overlays Coarse- 
grain screens Theory of colour Diagrams of colour Peculi- 
arities of pigments Permanency of pigments Yellow pigments 
Red pigments Blue pigments Green pigments Purple and 
orange pigments Brown pigments " Art " shades Three- 
colour printing Photographic falsification of colour 
Coloured screens Clerk-Maxwell's work Colour screens or 
niters Coloured light Pure pigments unknown General con- 
siderations Examination of trichromatic prints The half- 
tone dot Necessity for transparent inks Opacity of yellow 
pigments Supplementary key block Inks for cheques 
and bank notes Patent inks for cheques. 

Early Methods. Interesting details as to the use of 
coloured inks in printing in the early part of the last 
century may be gleaned from the large volume by Savage.* 
This contains many illustrations in colour, with a specimen 
block of each pigment employed. The latter are useful as 
witnesses of permanency, but the fact must be taken into 
consideration that these specimen tints have not been 
exposed to the action of light. Among the colours illus- 
trated we find bistre, sepia, smalt, cobalt and some others 
which are now seldom employed by the ink manufacturer. 

It is worthy of notice that Savage makes no allusion to 
the purchase of coloured inks, and we may presume there- 
fore that up to the date of this book, and possibly for 
some time afterwards, printers were dependent for these 
upon their own resources. 

Manufactured Inks. A later author, Ringwalt,^ re- 
marks that " in the present advanced state of ink-making" 

* Practical Hints on Decorative Printing, 1822. 

f The American Encyclopaedia of Printing. Philadelphia, 1871. 



168 INKS AND THEIR MANUFACTURE 

it is better for printers to rely upon the manufactured 
article than to attempt to make their own inks. And he 
suggests that the difficulty of reducing these inks and 
mixing them with varnish in the best way to meet the 
necessities of the work in hand, is quite enough in itself, 
without the trouble of compounding the inks being added 
to it. If, however, the printer should insist on being 
independent in this matter he is referred to Houglitorts 
book * for further information on the subject of ink- 
making. 

Referring to HougJiton, we find that he admits that 
coloured inks can be purchased ready for use, but com- 
plains that they are dear, and that the required tints 
cannot always be readily obtained. He advises the printer 
therefore to buy his own raw materials and to mix them 
for himself taking care that the colours employed are of 
the best. The appliances and materials necessary consist 
of a muller, a marble slab and palette-knife, a can of 
printer's varnish and the raw colours. He then gives a 
review of the best colours to use. 

Painters' Pigments. We may take it as a general rule 
that pigments used by painters can, with very few excep- 
tions, be adapted to the printing-press, always remembering 
that the painter is not limited to a certain thickness of 
material. He can if he likes, and as many do, pile on the 
paint with a palette-knife so that it lies on the canvas in 
prominent ridges. The printer, on the other hand, must 
use his colours in such thin layers that their thickness 
cannot be measured even by a micrometer. It is obvious 
that this means that the pigment used must have great 
body or covering power, unless it is intended by printing 
one colour above another to get a compound tint. 

Early Ignorance as to Proper Pigments. In a smaller 
book by Savage of later datef a chapter is devoted to 
coloured inks, in which he deplores the ignorance of 
printers and ink-makers concerning colours and their 
application to the press. He advises the use of slab and 
muller, and good printing ink varnish, and in cases where 
the ink shows a tendency to accumulate upon the type 

* Printer's Everyday Book, 1856. 

f On the Preparation of Printing Ink both Black and Coloured, 1832. 



COLOUKED FEINTING INKS 169 

recommends the addition of curd soap which must be 
rubbed into the ink with the muller. He then repeats in 
slightly amplified form the particulars of the different pig- 
ments which he gives in his previous work. It is interest- 
ing to note that he advocates the use of carmine for a 
crimson ink, but only for very particular purposes, adding 
naively, "I have been accustomed to pay for the best two 
guineas an ounce." 

The Half-Tone Process Block. The introduction of 
the half-tone photographic process block, which has largely 
superseded the art of wood engraving, caused quite a revo- 
lution in printing methods. The etched dots upon these 
blocks are so fine in character that the work is com- 
parable to a steel engraving rather than to one upon wood ; 
and if one cares to look up the files of any illustrated 
journal of the period when these blocks first came into 
use, he will see what deplorable things the printers made 
of them. Neither the paper nor the ink were good enough 
to meet the needs of these finely etched blocks ; and 
although we must regret the decline of the beautiful art 
of wood-engraving, we must put to the credit of the pro- 
cess block a revivification of the printer's art which has 
been beneficial from every point of view. 

Necessity for Cleanliness. Printers are beginning to 
see that under the new conditions cleanliness, as well as 
care, is needed at every stage of the work. When type 
and electros from comparatively coarse wood-cuts, both of 
which were treated with black ink only, were the sole 
requisites of the printer's art, the workshop was the home 
of grime, perhaps necessarily so. But now that the work 
entails the employment of delicately etched process blocks 
much greater care is needed. The place must not only be 
kept scrupulously clean, but a uniform temperature must 
be maintained if good work is to be produced. The com- 
mon use of the electric motor for driving the machinery 
has banished most of the dirt ; and the question of tem- 
perature is not a difficult one to solve. The black ink 
used for process blocks must be of the finest description, 
and it is found in practice that they take up far less ink 
than either type or woodcuts. The layer of ink is so very 
thin that it is a matter of necessity that it should have 



170 INKS AND THEIR MANUFACTURE 

good covering power, otherwise the impression will appear 
to be grey and flat. 

Overlays. These blocks require to have the pressure so 
adjusted that it is greatest in the shadows, less in the half- 
tones, and lightest of all in the high lights. This desi- 
deratum is secured by overlays, and a great improvement 
has been effected by the recent introduction of an overlay 
made of guttapercha on paper, which is produced by a 
photographic process. This overlay, which is specially 
adapted to the process block, has been introduced from 
America and is known by a patent name. 

Coarse- Grain Screens. In the case of rapidly printed 
newspapers on rotary machines, half-tone blocks made with 
coarse-grain screens are coming more into use every day 
and displacing the line-drawing it is often found advisable 
to use a finer grade of ink for the pages bearing the 
illustrations than for those containing the text. In higher 
class journals the custom has recently obtained of printing 
fine-grain half-tone blocks in coloured ink while the 
accompanying text is in black. This of course involves 
separate printing unless a two-colour machine is employed. 
The effect of the two colours on one page is often most 
artistic. 

Theory of Colour. It would be beyond the scope of 
this work to devote much space to the theory of colour, 
although we are fully alive to the undoubted advan- 
tages to be secured by all those having to deal with colour, 
by an understanding of the principles upon which that 
theory is based. There are so many excellent manuals 
upon the theory of colour, the harmony of colours, and 
upon the use of pigments generally, that all who desire to 
acquire knowledge upon these subjects will have no diffi- 
culty in finding instructors. 

Diagrams of Colour. Many diagrams have been pub- 
lished for showing at a glance the so-called primary colours, 
and their relation to the secondary and tertiary tints, but 
the most simple is a very old one which we here reproduce 
(Fig. 39), and in doing so we must express our regret that 
we cannot discover the name of its originator. It is 
extremely useful in at once fixing upon the mind the 
nature of colour relation so far as pigments are concerned. 



COLOURED PRINTING INKS 



171 



The central disc is black, which represents a mixture of 
the three primary colours surrounding the disc we find 
the primaries, yellow, red, and blue. In the next concen- 
tric ring are the three secondaries, made up of mixtures 
of the two primary colours which lie against them. Thus 




Fig. 39. Colour diagram. 

orange is a mixture of red and yellow, green of yellow and 
blue, and purple of red and blue. Here too we have a 
ready guide to the complementary colours, a mixture of 
any two of the primaries, constituting the complementary 
tint to the remaining primary. Thus green, made up of 
blue and yellow, is complementary to red ; orange to blue 
and purple to yellow. 



172 INKS AND THEIR MANUFACTURE 

In the outermost ring are the tertiary tints made up of 
mixtures of the secondaries, thus green and orange form 
citrine; orange and purple, russet; green and purple, olive. 

Peculiarities of Pigments. The worker who has 
hitherto confined his attention to black printing will find 
upon dealing with colours that he has difficulties to meet 
which at first may seem to be insuperable. Each coloured 
ink appears to have its own peculiarities, and where, with 
a black ink, it is possible to temper it with various media 
so as to alter its working qualities, coloured ink cannot in 
many cases be so tampered with. A colour can of course be 
modified by the addition of white to lighten it, or black to 
darken it ; but what we mean is, that where delicate colora- 
tion is necessary, the wholesale addition of turpentine, oil, 
varnish, &c., is not permissible. Inks of various colours 
are now purchasable which need no such additions. 

Permanency of Pigments. Up to recent times the 
colours employed in the manufacture of printing inks were 
with a few exceptions of mineral origin, and such colours 
are as a general rule permanent in their nature. And 
permanency is one of the principal considerations in the 
selection of a colour, unless the work that the ink is 
intended for be of quite an ephemeral character. 

Aniline Colours. When the aniline colours first became 
available in the arts, printers, like many others, were 
attracted by the gorgeous tints presented by them. The 
new dyes were quickly made into inks, and bizarre posters 
with colour schemes never before dreamt of even by those 
afflicted with acute chromatic aberration appeared on the 
street hoardings. But only for a brief time, for sunlight 
mercifully bleached out several of the colours before the 
prints were many hours old. Any one can test for himself 
the fugitive nature of most of these aniline colours by 
exposing any surface coloured with one of them under a 
negative in an ordinary photographic printing frame. 

It is the belief of many workers that this charge of 
instability which is brought with such good reason against 
the aniline colours will some day be removed, and that in 
course of time aniline colours will be produced to which no 
exception can be taken on this score. We shall see, when 
we come to consider the requirements of the three-colour 



COLOURED PRINTING INKS 173 

system of printing, that such colours are greatly in 
demand. 

The experiments of Prof. Church * on the stability of 
different oil paints exposed to the action of light and air 
under similar conditions for periods of two or five years are 
vory instructive, and supplement the experiments of Sir 
William Abney and Dr. Russell on moist water colours 
(p. 114). 

The following were some of the most important results 
obtained, the depth of the initial colour in each case being 
represented by 10 : 

Naples yellow- . -. . 10.0 No change. 

Madder red . ~ . . 10.0 

Madder carmine ... 9.5 ,, 

Madder brown . . 9.0 

Artificial ultramarine . . 10.0 

Prussian blue . . . 8.5 slightly greener. 

Indigo ..... 8.0 ,. 

Indian yellow . . . 8.0 slightly brown. 

Yellow ochre . . . 10 o browner. 

Crimson lake . . . i.o almost gone. 

Aureolin .... 9.0 no change. 

As coloured printing inks are essentially a kind of oil 
paint, it is not unjustifiable to assume that closely similar 
results would have been obtained with the same pigments 
incorporated with lithographic varnish. 

Fugitive Colours. Want of permanence is thus a 
fault which is to be attributed to other colours besides 
those derived from aniline ; and those who would seek 
information upon this point cannot do better than consult 
Professor Church's book, where a table is given in which 
pigments are divided into three groups Class I., contain- 
ing the truly permanent colours ; Class II., those which are 
subject to a certain amount of change, but which may be 
used ; and Class III., comprising those which ought to be 
definitely excluded from use. 

Following the order adopted in the table referred to, we 
will now briefly consider the various pigments which are 
of interest to the printer and manufacturer of printing 
inks. 

* Chemistry of Paints, p. 346. 



174 INKS AND THEIR MANUFACTURE 

White Pigments. The white pigments named in Pro- 
fessor Churctis list are three in number, baryta white, 
zinc white, and flake white. The first named is not used in 
the making of ink, but it is of secondary interest to the 
printer in that this description of white is much used in 
the preparation of surface paper, which is now so much in 
demand for the effective printing of half-tone process 
blocks. Zinc white, or zinc oxide, is much in request by 
the water-colour artist on account of its permanency ; but 
it is not so satisfactory for printing purposes as white 
lead or flake white. All these three pigments appear in 
Church's list as first-class pigments in the matter of per 
manency, if used for oil painting. But when the particles 
of lead carbonate are not wrapped up in oil, i.e., when 
used for water-colour painting, the pigment is rapidly 
attacked by any sulphurous contamination in the air, 
and quickly blackens. 

Yellow Pigments. Of yellow pigments there is a very 
great variety, and although printing in yellow ink is not 
by itself often called for, except perhaps in poster work, 
the admixture of yellow with other colours in the forma- 
tion of secondary and tertiary tints gives it an importance 
which it might not otherwise possess. We must remem- 
ber, too, that in the modern three-colour process yellow is 
one of the three primary tints upon which that process 
depends for its efficiency. 

The most important of all the yellows to the printer is 
lead chromate, usually known as chrome yellow. By mixing 
the neutral chromate with lead oxide yellows of various 
tones, including the orange, may be obtained. For lighter 
chromes, lead sulphate, while a mixture of lead chromate 
and sulphate is employed in the production of certain 
tints. Here again we have a series of pigments which, 
while unstable when employed as water colours, are com- 
paratively safe when locked up in oil or varnish, as in the 
manufacture of inks. Chrome yellow, combined with 
Prussian blue and with black, gives a great variety of 
greens. Vanadium yellow, king's yellow (prpiment), 
alizarine yelloiv, and alizarine orange are all liable to 
change, and the same may be said of yellow lake, brown 
pink, yelloiv madder, and Italian pink. Cadmium yellow 






COLOUEED PRINTING INKS 175 

and cadmium orange may be placed among the permanent 
colours, but they are too expensive for common use. Of 
all these yellows, chrome yellovj is to be preferred on 
account of its easy working and freedom from grittiness. 

Yellow ochre, Roman ochre, and other earths are durable 
pigments, and are of use to the printer when bright yellow 
tones are not required. They are also useful for admixture 
with Prussian blue and other pigments for the production 
of composite colours. Raw sienna and burnt sienna come 
under the same category, the first being a yellow and the 
second a brownish red. These last named pigments are 
extremely hard and require careful grinding. 

Bed Pigments. There are many red pigments which 
can be used in the preparation of printing inks. Ver- 
milion, which is found in the form of cinnabar (mercuric 
sulphide), in many parts of the world, or can be pre- 
pared artificially, is tempting because of its beautiful 
scarlet colour. But ink prepared from it cannot be em- 
ployed with lead type, for that metal decomposes the 
mineral and changes its colour. Otherwise there is no 
reason to suspect the permanency of vermilion when asso- 
ciated with oil or varnish, and Professor Church places it 
among the first-class pigments. 

Vermilion, prepared from native cinnabar, was used in 
the decoration of the walls of Pompeii, wax being the 
medium with which it was associated. The colour has not 
faded, although nearly twenty centuries have gone by 
since the doomed city was overwhelmed by the ashes from 
Vesuvius. We must, of course, take -into consideration 
that light has been excluded. The Chinese cinnabar is so 
pure in quality that it merely requires grinding to convert 
it into the well-known scarlet pigment. Vermilion of first- 
rate quality is expensive, and cannot come into common 
use as an ink. 

Madder. One of the most valued reds has always been 
that derived from the madder plant Rubia tinctorum of 
Linn83us and until comparatively recent times large 
tracts of land in .India, as well as in the Levant, Holland, 
and France, were devoted to its cultivation, chiefly for 
dyeing purposes. But owing to the synthetical produc- 
tion of its chief constituents, alizarine and purpurine, from 



176 INKS AND THEIR MANUFACTURE 

anthracene, the cultivation of the madder plant may now 
be regarded as a discarded industry. Anthracene is 
derived from coal-tar, and the colouring-matters which it 
affords are apparently identical with those formerly 
obtained from the madder plant. A great variety of dif- 
ferent reds, such as madder carmine, rose madder, pink 
madder, brown and purple madder, are obtained from 
alizarine and purpurine. The best qualities are fairly 
permanent, but some of the tints are liable to change 
their tone. The madders come under Class II. in Pro- 
fessor Church's list. 

Carmine. Carmine, a very unstable compound prepared 
from the cochineal insect, is sometimes employed to give 
a fictitious brilliancy to dull reds, but it is so much more 
expensive than alizarine that it does not now often come 
under the notice of the ink manufacturers. 

Iron Oxide. Indian Eed, Turkey Red, Persian lied, seem 
to be different names for the same thing, ferric oxide, or 
iron rust. Although not suitable for fine work when used 
by itself, it is valuable for mixtures with other pigments. 
Light red and Venetian red are pigments of similar tint, 
and are varieties of red ochres. 

Blue Pigments. Ultramarine is perhaps the most 
beautiful of the blue pigments, whether it be natural, i.e., 
made from lapis lazuli, or artificial. The artificial ultra- 
marine, one of the cheapest colours, is alone likely to come 
under the notice of the printer. Ink made from it is 
unsatisfactory. It will not work well, and the impressions, 
even under the hand of a skilled man, are uneven and 
rough in appearance. 

Prussian Blue, on the other hand, has many good quali- 
ties to recommend it, and it makes a variety of useful 
tints when mixed with other pigments. It is transparent, 
and has great tinctorial power, but when much diluted, or 
made into a light tint by admixture of a white pigment, 
is seen to have a greenish hue. Ink made from Prussian 
blue is generally regarded as being permanent, but it is 
liable to become pale when exposed to alkaline fumes, 
such as ammonia. For this reason Prussian blue inks 
should not be employed in the printing of labels for soap 
or other substances of an alkaline character. 



COLOURED PRINTING INKS 177 

Cobalt is a permanent blue, but is seldom used by the 
printer ; and the same may be said of indigo, an unstable 
colour, but one which, with certain yellows, affords useful 
greens. 

Green Pigments. Green pigments for use in the 
printing press are generally compounded of Prussian Hue 
and chrome yellow, both of which pigments have already 
been considered. But chromium oxide, a remarkably stable 
compound, is also occasionally used for very fine printing, 
such as that of bank notes. 

Many greens, like Emerald green, Scheele's green, Paris 
green, &c., are combinations of copper and arsenic, which 
are highly poisonous. The first-named possesses a tint 
of great beauty, which cannot be equalled by any combined 
pigments, but it is such a very bad working colour that it 
is not made up as a printing ink. It has, however, some- 
times been dusted on to a printed varnish in the same way 
that bronze powder is attached to such varnish ; but the 
practice must be fraught with so much danger to all con- 
cerned that only ignorance of the results to be expected 
could pardon its employment in this way. 

Purple and Orange Pigments. The other secondary 
colours, orange and purple, are generally compounded 
from the primaries, and they do not need further descrip- 
tion at our hands. An endless variety of different tones 
is procurable by using the constituent primaries in 
varied proportions. 

Brown Pigments. Under the head of brown pigments 
come a number of earths which owe their coloration 
principally to iron oxide, such as, ochre, umber, Vandyke 
Iroiun, &c. These earth colours are permanent, and are 
useful in compounding the coarser kind of printing inks. 
But it should be noted that for the printing of delicate 
half-tone blocks such natural colours are quite unsuitable. 
They always retain their gritty character, even after the 
most thorough grinding, and this has a very prejudicial 
effect upon the blocks, which under such treatment soon 
exhibit signs of wear and tear. 

" Art Shades." For such work browns of far richer 
tone and finer substance may be made by mixing alizarine 
and other reds with bl^ck, to which may be added chrome 

M 



178 INKS AND THEIR MANUFACTURE 

^yellow, Prussian blue, and other colours. So-called 
"art shades " in printing inks, made up of secondary and 
tertiary colours with a certain admixture of black to 
sadden the general tone, are now much in vogue. If the 
component colours be carefully selected, a half-tone block 
printed in one of these inks, provided that it has plenty of 
contrast between full shadow and light tint, appears as if 
produced by two printings. Such inks have been described 
for this reason as double-tone inks. 

It may be mentioned here that such colours as ochre, 
umber, &c., which are rich in oxygen, do not require the 
addition of any separate drying medium when used in the 
manufacture of printing ink. 

THREE-COLOUR PRINTING. 

Trichromatic Printing. It is when we come to con- 
sider the effect of the introduction of the process block 
upon colour work that we find changes of the most 
radical character, not, of course, in the production of mere 
monochrome impressions, but in the practice of the 
three-colour, or, as it is often called, the trichromatic 
method of block printing. 

It is not within the scope of this work to consider how 
far the modern three-colour method of printing will 
supersede chromo-lithography ; probably there will be 
found an ample field of employment for both processes. 
But it will be necessary to give a brief outline of the 
principles upon which this modern method of producing 
pictures in colour depends. Like the half-tone process 
block, the three-colour method of printing is born of the 
art of photography. 

Photographic Falsification of Colour. It has long 
been known that the photographic plate gives a very 
false rendering of coloured objects, blue and violet being 
represented as white, while the warmer tints are shown as 
black. To understand the underlying cause of this falsi- 
fication it is necessary to refer to Fig. 40, which repre- 
sents the solar spectrum in triplicate. In the centre it is 
shown diagrammatically in the usual manner, with the 
principal Fratienhofer lines marked by initial letters. 










I 




< 

03 






















li- 
es 
























COLOURED PRINTING INKS 179 

Also indicated in this diagram are the prismatic colours, 
from violet to red. Above the diagram the graduated 
strip shows how the spectrum appears to the eye, the 
greatest intensity of the light culminating in the yellow 
region, and fading away gradually into the red at one end 
and into the violet at the other end of the scale. 

Below the diagram we see a similar graduated strip, 
representing the solar spectrum as reproduced on the 
photographic plate y and we are able to note at once that 
the place of greatest intensity is not near the yellow 
region, but is far away at the violet end of the spectrum. 
This is a graphic manner of explaining why upon the 
photographic picture blue is represented as white, and green, 
yellow and red as black, or nearly so. 

Isochromatic Plates. To Professor Vogel is due the 
discovery that, by associating with the gelatine emul- 
sion which constitutes the surface of a photographic 
plate certain aniline dyes, its sensitiveness to what we 
generally call the warmer colours of the spectrum is 
much increased. These plates are known as isochro- 
matic, or ortho-chromatic, and are used in the camera in 
conjunction with a coloured screen. The exact position 
of this screen is unimportant, but a convenient plan is 
to mount the lens of the camera upon a kind of false 
front with a slit behind it in which the screen can be 
inserted. 

Coloured Screens. A simple yellow screen or filter 
consisting of a glass trough holding coloured liquid, or 
more conveniently a glass plate coated with coloured 
gelatine, will, in conjunction with an isochromatic plate, 
be of service in ordinary landscape work. For example, 
the brilliant yellow blossoms of gorse in the springtime 
would be represented as black by an ordinary plate, but 
with the isochromatic plate and screen they would be 
almost white. The foliage tints of autumn can also be now 
rendered in a manner far more true to nature than was 
possible before Professor Vogel's discovery. 

Photography and Coloured Objects. But when we 
come to the representation by photography of oil and 
water-colour pictures, and different works of art in which 
colour is an important feature, far more care is necessary 



180 INKS AND THEIR MANUFACTURE 

in the selection of a proper light filter. The word 
filter is used advisedly, for the function of the screen 
is to prevent certain rays passing it, while it gives pas- 
sage to others. In other words, the required colour is 
filtered from its associated tints. 

Clerk-Maxwell's Work. The pioneer in this work was 
Professor Clerk-Maxwell, who as long ago as the year 1861 
showed in an imperfect manner, for the isochromatic 
plate had not yet been conceived, that three pictures 
photographed from one coloured original, but each under 
a differently coloured screen or filter, would, when com- 
bined under suitable coloured lights, amalgamate into a 
fair representation of the object photographed. MaxweWs 



B C 



H 





Bluue, 



Fig. 41. Clerk-Maxwell's colour curves. 

colour curves have formed the basis of all work in this 
direction since his time. A representation of these curves 
is given at Fig. 41. We here see the proportion of 
the spectrum of which each of the three-colour filters 
should consist, the red taking in a certain part of the 
yellow and green, the green overlapping the red and 
blue, while the blue comprises the violet and part of the 
green. 

Colour Screens or Filters. By mixtures of certain 
aniline dyes, and staining with them glass plates coated 
with gelatine, screens or light filters can be made to closely 
approximate in tint to Maxwell's curves. In photograph- 
ing a coloured object, say an oil painting, three negatives 
are made, each under its respective colour filter. From 
those negatives half-tone blocks are prepared, and it is the 



COLOURED PRINTING INKS 181 

printer's business to superpose the images from those 
blocks in three coloured impressions so as to give a fair 
representation of the original coloured object. 

Coloured Light. In dealing with coloured light we 
find that if we mingle upon a screen the colours red, green 
and blue, from three lanterns we produce white, or an 
approach thereto, for white light is composed of all the 
colours of the spectrum. But if we mix together pigments 
of the same tones we produce black. In the one case we 
are working with coloured lights, and in the other with 
coloured shadows. And when we come to handle pig- 
ments such as are employed by painters, and in the manu- 
facture of printing ink, we must regard as primary or 
foundation colours, blue, red, and yellow. 

Pure Pigments unknown. There is unfortunately no 
such thing as an absolutely pure pigment, and we can 
never hope really to match the rainbow colours of the 
prism, otherwise it would be possible to follow with 
some accuracy tht? guide afforded by Maxwell's curves. 
The ideal pigments for printing in three colours have 
yet to be found ; and ink makers are so alive to the 
importance of the subject that they are devoting much 
attention to the production of inks which shall, as far 
as possible, come up to the scientific standard. 

General Considerations. The difficulty with which 
printers have hitherto had to deal is that the ink makers 
have not worked hand in hand with the makers of light 
filters to reach one common goal. The colours of screens 
and of the inks to be associated with them should be fixed 
and unalterable. Many workers have been in favour of 
producing the three inks in the first place, taking care that 
the pigments are as pure in tone as it is possible to procure 
them, and then of adapting the colour screens or filters 
to the pigments so chosen. At present there seems to be 
much confusion reigning, owing to so many workers acting 
independently of one another ; and it thus comes about 
that A.'s blocks will give results with inks made by C., 
which are not possible if B.'s inks are used. That this 
confusion is quite unnecessary must be apparent when we 
remember that the exact colours of the inks and screens 
are based upon scientific principles. 



182 INKS AND THEIR MANUFACTURE 

Examination of Trichromatic Prints. In drawing 
this chapter to a conclusion, we may note that those who 
would get a fair idea of the way in which separate process 
blocks can be made by three printings to give all the 
varied tints of a polychromatic original object, will learn 
far more by five minutes' careful examination of a good 
specimen of three-colour printing than they can from 
many pages of description. 

To examine the print a good magnifying glass is needed, 
for it is requisite to separate the dots of which the picture 
is composed, and to note their colour and relation to one 
another. 

The Half-tone Dot. As in all half-tone blocks, these 
dots are large and crowded together in the shadows, and 
comparatively small and widely separated in the lights. 
In the deepest shadows of all the dots, yellow, red, and 
blue are superposed one on the other to form a near 
approach to black. In other places we find two dots of 
different colours printed above one another, and giving 
just the same effect as the same two colours mingled on a 
palette. In other places we find dots of different colours 
placed in juxtaposition so that the eye mixes them into 
a compound tint. 

Necessity for Transparent Inks. Now it is obvious 
that one of the first requisites of the inks used for these 
built-up tones is that they should possess transparency. 
An opaque colour, like vermilion or ultramarine, would at 
once blot out anything already printed beneath it. We 
can therefore say at once that such colours are inad- 
missible for this class of work. 

Opacity of Yellow Pigments. The yellow must be of 
a sulpbur hue, and it is not easy to hit upon exactly the 
right pigment. A transparent yellow is not at present to 
be found which is suitable, but the difficulty of opacity is 
partly overcome by printing the yellow block first. Next 
in order comes the red, and there is nothing better than 
the madder lake which is produced from alizarine. We 
have already seen that its permanency is good, and it is a 
very transparent colour. For blue we must use Prussian 
blue, and, as far as possible, the three colours must be so 
compounded that they possess equal covering power. 



COLOURED FEINTING INKS 183 

Supplementary Key Block. Some workers have 
advocated the use of a supplementary key block printed in 
black or brown in addition to the usual trichromatic 
blocks. But this can only be necessary when the original 
screens, or the coloured inks, are at fault, or when the 
screens do not represent truly the complementaries of the 
colours used. If the right colours are employed the 
superposition of the three inks should produce black, and 
different shades of grey should be possible by varying the 
proportions of each. The key block is regarded by the 
foremost workers as a superfluity. 

INKS FOR CHEQUES AND BANK NOTES. 

Under the head of " Printing inks that change colour 
on the application of an acid," Savage* tells us of a black 
ink, the method of making which was for a long time kept 
a profound secret "by one house in the city of London," 
which was designed to prevent fraudulent alterations in 
bankers' cheques, &c. And he suggests that, in addition 
to this precaution, the whole paper of such documents 
should be covered with a delicate lace pattern in a light- 
coloured ink, so that should any attempt be made to 
remove writing upon such a draft by means of acid, the 
pattern and the printed words would disappear as well as 
the writing ink. The black ink, for which he furnishes a 
recipe, is made of galls, iron, and logwood, which is pre- 
cipitated, dried, and ground with soap, turpentine, and 
balsam of capivi. 

For the purpose of printing the lace-like pattern over 
the surface of the paper he recommends the lake of com- 
merce,ground up with varnish and a large proportion of curd 
soap. This ink he actually tried, and found that it would 
not resist oxalic acid, but he states that any colour of 
vegetable origin might be adapted to the same purpose. 
He expresses the hope that, from the hints which he has 
given, the subject will be pursued and the method made 
perfect and asserts that if he should thus prove to be 
the means of preventing the commission of crime, it would 
be a source of the highest gratification to him. 
* The Preparation of Printing Ink, 1832. 



184 INKS AND THEIR MANUFACTURE 

In the earliest attempts to guard against fraud by 
alterations in cheques, &c., attention was directed to 
the writing ink to be used, and numerous so-called 
" safety inks " (p. 207) were devised. Obviously, how- 
ever, such inks would only be used to a limited extent, 
and the necessity for them has been largely obviated by 
the introduction of various methods of printing the 
groundwork of the cheque with special inks that would 
permanently change colour on the addition of any of 
the usual reagents employed to remove ordinary iron 
gall inks. 

Patent Inks for Cheques, &c. A process patented by 
Seropyan (Eng. Pat., No. 1744 ; 1857) was devised to pre- 
vent the counterfeiting of bankers' drafts and other docu- 
ments by photography. Two or more colours were used, 
each of which " absorbed light." The groundwork of 
the note was printed in one of these (e.g., yellow, red or 
orange), whilst the other was made into an ink for printing 
the design and figures on the note, and was as fugitive as 
the ground colour. An ink of this type consisted of iron 
hydroxide and gallic acid ground in boiled linseed oil. 
Documents thus printed gave only a blurred photographic 
copy, whilst any attempts to remove the ground colour 
simultaneously removed the design. Vogel's discovery of 
colour sensitive plates destroys whatever value there was 
in this invention. 

In Moss's patent (Eng. Pat., No. 348 ; 1859) the paper 
pulp for the notes was incorporated with a pigment, such 
as chromium oxide or burnt clay ; whilst an ink for print- 
ing the notes contained burnt China or other clay and 
sulphur, with or without a pigment. It was stated that 
any attempt to remove the colour or printing would render 
the note useless for circulation. 

A permanent printing ink for bank notes invented by 
Edson (Eng. Pat., No. 3204; 1863) consisted of a com- 
pound of stannic oxide with chromium oxide or other 
metallic oxide. 

In 1876 Pinkney (Eng. Pat., No. 4470) claimed a pro- 
cess of treating the note with a substance that would form 
an insoluble compound with ordinary writing ink, and 
mentioned in particular soluble non-deliquescent ferro- 



COLOUEED PRINTING INKS 185 

and ferri-cyanides with an aniline or vegetable colour as 
suitable for the purpose. 

In Nesbit's patent (No. 4204 ; 1879) ordinary litho- 
graphic ink was dried, powdered, and mixed with an 
aniline dye-stuff soluble in water, the whole being mixed 
with turpentine or other liquid which would not dissolve 
the aniline dye-stuff. Cheques printed with this ink would 
be smeared on applying any aqueous reagent to remove 
writing. 

A special method of preparing paper for cheques by 
immersion in copper sulphate and ammonium carbonate 
solution, and subsequently in an alkaline solution of 
cochineal with alum and glycerin, was provisionally pro- 
tected by Haddan (Eng. Pat., No. 4997 ; 1879). This 
paper would change colour on contact with the reagents 
used to remove writing ink. 

A process with the same end in view was patented by 
Dupre and Hehner (Eng. Pat., No. 375 ; 1881). The pre- 
paration used for printing the note consisted of a sulphide 
insoluble in water, but acted on by dilute acids (e.g., zinc 
sulphide), with lead carbonate or other salt of a heavy 
metal. The mixture was worked into a paste with glycerin, 
treacle, and gum arabic, and could be used for printing 
invisible characters on the cheque, or added to the coloured 
paste for printing the groundwork. On applying acid, 
alkali, or cyanide to a cheque thus treated, dark stains 
would be produced immediately. 

A method of preventing the obliteration of printing ink 
by means of solvents for oils, and especially the cancelling 
marks on postage stamps, was devised by Nesbit (Eng. Pat. 
No. 949 ; 1883). It consisted of the use of a printing ink 
prepared by incorporating an extract of alkanet root with 
oil. Any attempts to remove ordinary printing ink would 
blur the printing don'e with this ink. In 1 896 Webb (Eng. 
Pat., No. 26,992) patented an aniline safety ink for copper 
and steel-plate printing of cheques and the like. 






SECTION III. 

INKS FOR MISCELLANEOUS 

PURPOSES. 

CHAPTER XII. 

COPYING INKS. 

CONTENTS. Various copying inks Patent copying inks 
Copying papers Copying ink pencils Manifold copying 
apparatus. 

MOST writing inks are capable of yielding one or more 
copies when pressed with a suitable moist paper soon after 
writing. Thus an ordinary iron gall ink of the old type 
will give a faint copy before it has become completely 
oxidised, but when once the pigment has become com- 
pletely insoluble copies can no longer be taken. 

As the process of copying tends to make the original 
writing too faint, it is necessary to have an additional 
quantity of pigment in the ink, together with a certain 
proportion of gum or other adhesive material to attach this 
excess of colouring-matter to the surface of the paper, and 
to protect it from too rapid oxidation. 

In the case of " alizarine " inks the irontannate becomes 
insoluble as the writing dries, but the indigo remains 
soluble in water, so that a faint blue copy can be taken at 
any subsequent period by pressing the writing with a 
damp sheet of paper. 

Logwood inks yield reddish-grey copies, which gradually 
oxidise and become black. When the writing is com- 
pletely dry only faint copies can be taken. 



COPYING INKS 187 

Dextrin is sometimes employed in place of gum to form 
a sort of varnish over the writing to prevent early oxida- 
tion. Sugar, too, is frequently added for the same pur- 
pose, but has tbe drawback of leaving the writing more 
or less sticky. 

Viedt * considers that many copying inks contain too 
large a proportion of adhesive substance, and is of opinion 
that from 30 to 50 grms. of gum arabic per litre is quite 
sufficient for a good ink. 

A small amount of glycerin is a common constituent of 
copying ink, its object being to prevent the gum from 
altogether drying. If, however, it be added in too large 
an excess the ink will smudge, as is the case with a certain 
commercial copying ink that contains as much as a third 
of glycerin. 

Even in Bottger's copying ink (infra) the proportion of 
glycerin (120 grms. per litre) is too high, and in Viedt'' 's 
opinion only a sixth of this amount is required to make an 
excellent copying ink on those lines. 

Speaking generally, iron gall and logwood inks should 
contain from 30 to 40 per cent, less water than inks 
of the same formula intended for use as writing inks 
only. 

Various Copying Inks. Of the numerous published 
formulae for copying inks the following are selected as 
typical, whilst others can easily be calculated by modify- 
ing the composition of writing inks given (pp. 93-99), 
in accordance with the general considerations given 
above : 

Starts Patent Copying Ink.-\ Logwood extract, 
250 grms. ; iron sulphate, 17 grms. ; copper sulphate, 
17 grms. ; alum, 100 grms. ; and sugar, 50 grms., in a 
litre of boiling water. The solution is subsequently mixed 
with 1 6 grms. of potassium chromate, 100 grms. of 
glycerin, and 2OO grms. of sulphindigotic acid. 

Bottger's Alum Logwood Copying Ink.\ One part of 
alum, 2 of copper sulphate, and 4 of logwood extract are 
boiled with 48 parts of water, and the solution filtered. 

* Dingier 1 s polyt. Journ., 1875, ccxvii. 148. 

t Ibid. 76. 

J Ibid. 1859, cli. 431. 



188 INKS AND THEIR MANUFACTURE 

Copies made with this ink are faint at first, but soon 
become dark. 

A later modification of this ink was made by Bottger* in 
the following manner: Logwood extract 30 grms. and 
crystalline sodium carbonate, 8 grms. are boiled with 
250 c.c. of water, and the solution mixed with 30 grms. of 
glycerin (sp. gr. 1.25), I grm. of potassium chromate, 
8 grins, of powdered gum arabic, and (preferably) about 
I grm. of copper sulphate to strengthen the colour. 

Dtlidon's Patent French Copying Ink.^ Galls, 10 grms.; 
ferrous sulphate, IOO grms. ; and logwood, 300 grms. ; 
are boiled with i| litres of water down to I litre. The 
solution is then mixed with 250 grms. of molasses, 
15 grms. of gum, and 5 grms. of alcohol containing 
5 grms. of an essential oil as preservative. 

Dieterich's Violet Logwood Ink.\ Logwood extract 
solution (20 per cent.), 600 ; sulphuric acid, O'5 ; mixed 
with a solution of aluminium sulphate, 40 ; oxalic acid, 
40 ; potassium carbonate, 40 ; potassium bichromate, 4 ; 
and phenol, I ; in 250 parts of water. This ink yields 
excellent copies. 

DietericKs Gall Copying Inks. Dieterich has prepared 
copying inks from oxidised gall extract and oxidised 
tannin solution prepared as described on p. 96. 

Mack Oxidised Gall Ink. 900 parts of the oxidised gall 
extract with 4 of sulphuric acid (sp. gr. 1.835) an d 60 
of ferrous sulphate, decanted after three weeks and diluted 
to a litre. 

Mack Oxidised Tannin Ink. 600 parts of oxidised 
tannin solution mixed with a solution of 60 parts of 
ferrous sulphate in 350 parts of water, filtered after 
three weeks and diluted to a litre. 

For coloured copying inks, these inks are mixed with 
various aniline dyes, such as phenol blue 2-5 parts per 
litre ; 6 of Ponceau red ; 6 of aniline green ; 1-5 of phenol 
blue and 2-5 of aniline green (for blue-green); 1-5 of 
phenol blue and 2.0 of Ponceau red (for violet), &c. 

* Dingier" 1 s polyt. Journ., 1869, cxci. 175. 
f Wagner's Jahres tier. , 1873, xix. 842. 
j Pharm. Manual, 1897, P- 685. 
Ibid. p. 683. 



COPYING INKS 189 

Aniline Copying Inks. Many of the commercial copy- 
ing inks are prepared from aniline colours, which, being 
soluble in water and not undergoing oxidation, enable 
copies to be taken at any subsequent period. 

Dietericli * gives the following formulae for such aniline 
copying inks : 

Violet. 20 of methyl violet, 3 B, in 940 Q warm water, 
with 10 of sugar, and 2 of oxalic acid. 

Blue. 10 of resorcin blue in 950 of water, with 10 of 
sugar and 2 of oxalic acid. 

Red. Eosin, 25 ; sugar, 30, in 100 of cold water ; 
subsequently filtered. 

The following dye-stuffs manufactured by the Badische 
Company are suitable for copying inks : 

Violet Inks. (a) Crystal Violet, the hydrochloride of 

hexamethylpararosaniline. 

(b) Methyl Violet and III. extra N, which are of 

similar chemical composition. 

Green Inks. Diamond Green, B and G (cf. p. 117). 
Red Inks. Diamond Magenta and Magenta Powder, 

which are mixtures of the hydrochloride and 

acetate of pararosaniline, and the corresponding 

salts of rosaniline respectively. 

Safranine T. extra, being phenyl- and tolyl-tolu- 

safranin chlorides. 
Black Inks. A combination of the above violets, 

greens, and reds with chrysoidine (diamido- 

azobeuzol hydrochloride) yields a black copying 

ink. 

Patent Copying Inks. Numerous British patents 
have been taken out for the preparation of copying inks 
aud papers, of which the following are the more im- 
portant. The modern method of copying by means of 
pressure and a special ink is due to James Watt, the 
engineer (Eng. Pat., No. 1244 ; 1780), whose copying press 
was of the same form as in use to-day. The addition of 
glycerin was first claimed by Henry (Eng. Pat., No. 1132, 
1858), whilst Roberts (Eng. Pat., No. 1213 ; 1862) added 

* Pha^m. Nawual, 1897, p. 687. 



190 INKS AND THEIR MANUFACTURE 

molasses and an extract of albemosch seeds, in addition to 
glycerin. The use of glycerin was also claimed by Win- 
stone (Eng. Pat., 1996 ; 1858), by Cooke (Eng. Pat., No. 47 ; 
1869), an d by Coen (Eng. Pat., No. 3247; 1891). In 
Conrad and Lilleys patent (No. 2011, 1890), indigo 
carmine, aniline black, glycerin and magnesium chloride 
are added to an ordinary iron gall ink; whilst the addition 
of a deliquescent salt, such as ammonium nitrate, with the 
glycerin is protected by Conrad (Eng. Pat., No. 10,401, 
1890). 

Aniline dye-stuffs enter into the composition of several 
of the patented inks, that of Kwayser and Hasak (Eng. 
Pat., No. 4606; 1878), consisting solely of an aqueous 
or alcoholic solution of an aniline colour. 

Copying inks in the form of a powder were patented 
by By ford (Eng. Pat., No. 974; 1876) and by JacobsoJin 
(Eng. Pat., No. 1586; 1878), the latter being prepared by 
evaporating to dryness a solution of aniline dye with 
sugar, gum, &c. 

Copying Papers. Of special copying papers that of 
Piffard (Eng. Pat., No. 10,905 ; 1890) was prepared by 
treating paper with a saturated solution of gallic acid, 
and was used with an iron ink. In Beaks' patent (No. 
17,373 ; 1890), the paper consists of tissue paper saturated 
with a solution of loaf sugar and silver nitrate in a 
mixture of water and glycerin, whilst the ink is an iron 
gall logwood ink containing glycerin and vegetable black. 
Both of the above inks are stated not to require a copy- 
ing press. 

Another special copying paper is that protected by 
Brown (Eng. Pat., No. 3807 ; 1900), which is coated on one 
side with hardened gelatin, and on the other with a 
deliquescent salt such as calcium chloride and a solution of 
a substance not affected by ordinary ink. This paper does 
not require damping. 

Copying Ink Pencils. These consist of a base, such as 
powdered graphite and kaolin clay mixed with a very con- 
centrated solution of methyl violet or other aniline dye- 
stuff into a paste, which is pressed into sticks and dried. 
In Vicdt's* opinion the use of gum arabic as a binding 
* Dingier' s poly t. Jour :i., 1875, ccxvi. 96. 



COPYING INKS 191 

material is less suitable. Provisional protection was 
claimed by Petit (Eng. Pat., No. 4090, 1874) for a copying 
ink pencil prepared in this way. 

Manifold Copying Apparatus. The well-known 
simple apparatus known as a graph is composed of a stiff 
gelatin bed, which receives the impression of the writing 
and enables several copies to be taken. The ink usually 
consists of an aqueous solution of methyl violet or other 
soluble aniline dye. This type of copying apparatus was 
patented by Eoscfcld in 1879 (Eng. Pat., No. 2256), the 
block consisting of gelatin, glycerin, molasses or sugar, 
acetic acid, and iron oxide, with sodium bisulphite to 
prevent decomposition of the gelatin. Special aniline 
and metallic inks for manifold copying apparatus were 
also patented by Hardt (Eng. Pat., No. 4187 ; 1879). 

Another copying apparatus of the same type, protected 
by Schmitt (Eng. Pat., No. 948 ; 1881), contained glycerin 
and chrome alum in the jelly, whilst the ink contained a 
colour, such as indigo and a uranium salt, and had a 
chemical action on the bed. The impression produced on 
the bed was capable of receiving printing ink. The 
drawback of gelatin copying apparatus is that the jelly 
soon becomes saturated with the aniline ink and is no 
longer capable of yielding clean copies. This is obviated 
in the apparatus protected by Smith (Eng. Pat., No. 7149 ; 
1888), which consists of a slab composed of a mixture of 
china clay, starch, glycerin, and water, from which the 
impression can be completely removed by means of a 
sponge after use. The ink is a solution of an aniline 
colour in a mixture of water, alcohol, and hydrochloric 
acid. 



CHAPTER XIII. 

MARKING INKS. 

CONTENTS. The ink plant of New Granada The Indian 
marking nut The Cashew nut Ehus toxicodendron Rhus 
venenata Khus radicans Other vegetable juices Chemical 
marking inks Silver inks Gold marking inks Platinum 
marking inks Marking inks containing other metals Aniline 
marking inks Indigotin marking inks Alizarine marking 
ink Examination of marking ink Marking ink pencils. 

NATURAL VEGETABLE INKS. 

NUMEROUS plants contain a juice, which is oxidised on 
exposure to the air, yielding black or brown pigments, 
often of great durability; and such natural inks have been 
employed in various parts of the world, either for writing 
or for marking linen. 

Jametel* quoting from ancient Chinese documents, states 
that prior to about 2697 B.C. the Chinese used a kind of 
vegetable varnish for ink, and not the product which is now 
known as Chinese or Indian ink. It is probable that this 
ink was the juice of a species of Rhus (vide infra). 

The Ink Plant of New Granada. According to 
Johnson f the juice of Coriaria thymifolia, known locally 
as chauci, or the "ink plant," is at first red, but rapidly 
changes in colour, becoming deep black in a few hours. 

The juice can be used as ink without any treatment, and 
gives a very stable writing, which is not affected by sea- 
water. Johnson states that all the older documents in 
Spanish South America were written with this ink. 

It is also a native of New Zealand, where too it goes by 
the name of the " ink plant." j 

* Loc. cit., Introd. p. x. 

t Universal Cyclopedia, New York, 1894, art. Inl: 

| Smith, Diet, of Economic Plants, p. 132. 



MARKING INKS 



193 



The Indian Marking Nut. The fruit of the Indian 
tree Anacardium orientale, which is now termed Seme- 
carpus anacardium (Fig. 42), has loDg been known as the 
" marking nut," from the fact that its juice makes a very 
dark and durable stain on linen or paper. 




Fig. 42. Indian marking nut (Semecarpus anacardiuni). 

The tree is found throughout the hotter parts of India, 
though not in Ceylon, and is also met with in the West 
Indies and in Northern Australia. The ripe fruit is yellow 
in colour, and is eaten after roasting by the natives. As 
met with in commerce it is a black oval or heart-shaped 

N 



194 INKS AND THEIR MANUFACTURE 

substance, about 2 cm. in length, and the same in breadth, 
and J cm. thick. The white kernel is covered by a reddish 
pellicle. 

The natives prepare the ink from the unripe fruit, and 
use it when mixed with quick lime for marking cotton and 
linen, on which it produces a very permanent mark.* 
The dried juice is also extensively employed in the 
manufacture of a black varnish. 

Lewis\ found that the juice required warming to make 
it flow freely. The writing done with it was first reddish 
brown, but rapidly became deep black and was very in- 
delible. 

The brown oil from the mesocarp dissolves in potassium 
hydroxide solution, giving a green solution, whilst the 
alcoholic solution becomes black on the addition of basic 
lead acetate. 

The juice has a very irritant action upon the skin, 
producing symptoms similar to eczema, and the same 
effect is said to be produced by the fumes given off on 
roasting the nut. 

We have made a number of experiments with the dried 
nuts. The black viscous juice surrounding the kernel of 
these had a characteristic aromatic odour and produced 
a light brown stain, which gradually darkened on exposure 
to the air. 

A decoction of the broken nuts in boiling water 
rendered alkaline with ammonia yielded a dark fluid, and 
the characters made with this on paper or linen were 
dark brown, and very resistant to the action of reagents. 
They were not removed by bromine, oxalic acid, or 
hydrochloric acid, whilst alkalies rendered them darker. 
They were soluble, however, in ether. 

Kindt's I method of preparing the ink was to extract 
the nut with a mixture of absolute alcohol and sulphuric 
ether to evaporate the extract to the required consistency. 
The writing done with this fluid on the linen was 
moistened with lime water or an alkaline solution to turn 
it black. Kindt found that it was capable of resisting 



* <rrjfji,cioi> = a mark, and Kapiros = fruit. 
t Philosophico-Technlcuni, 1763, p. 329. 
j Dingier' s poly t. Journ., 1859, cliv. 158. 



MARKING INKS 



195 



boiling with hydrochloric acid and potassium chlorate, 
though rendered faint by the treatment. 

The Cashew Nut. This is the fruit of another member 
of the Anaccirdiaccce, A. occidentale, a tree somewhat 




Fig. 43. Cashew nut (Anacardium occidentale). 

resembling the walnut in size and appearance (Fig. 43). 
It is found in India, the West Indies, and tropical parts 
of South America. 

The kidney-shaped fruit is about an inch in length, and 
projects from a fleshy pear-shaped fruit-stalk. The milky 



196 INKS AND THEIK MANUFACTURE 

juice in the stem of the tree becomes hard and black on 
exposure to the air, and is used locally as a varnish. 

Lewis* in 1763 found that the dark viscous juice within 
the nut when applied to cotton or linen gave a brown 
stain, which was very permanent, but did not become 
black upon exposure to the air. 

The brown oil in the fruit is soluble in potassium 
hydroxide solution. On treating an alcoholic solution 
with basic lead acetate a red precipitate is obtained. 

In 1847 Staedeler separated a vesicating principle, 
which he termed Cardol (C 21 H 30 2 ), and a reddish yellow 
oil, which he termed Anacardic acid. 

Rhus toxicodendron. This is a poisonous plant, origin- 
ally indigenous to N. America, where it was known as the 
" poison tree " by the natives of Carolina,-)- and to Japan, 
where the juice has long been used as a varnish. "f 

The milky juice rapidly darkens on exposure to the air, 
and has frequently been recommended as an indelible ink, 
especially for marking linen. Thus the Abb6 Mazcas^. 
stated that he had made experiments on this point, and 
found that the writing still remained black after five 
years, during which period the linen was repeatedly 
washed. 

The plant, which is also known as the poison ivy and 
poison oak, grows to a height of several feet, and 
produces small green flowers (Fig. 44). The leaves are 
employed commercially in the manufacture of a black 
stain, and are collected for this purpose from May to 
July, whilst the plant is in bloom. The juice of the leaves 
will raise a blister on the skin within forty-eight hours, 
and even the vapours given off by the living plant, 
especially by night, produce vesicular eruptions on the 
skins of certain people peculiarly sensitive to its effects. 
Porcher found that the acrimonious vapours emitted 
during the night contained hydrocarbons, and would 
ignite when brought into contact with a flame. 

Kluttel, who examined the constituents of the plant in 
1858, found that it contained an "iron-greening" tannin. 

* loc. cit. 

f Miller, Trans. Roy. Soc., 1755, xlix - l6l 

| loc. cit., xlix. 157. 



MARKING INKS 



197 



In 1865 Maisch and Stilti* isolated a volatile substance 
which reduced silver nitrate solution and gave a white 
precipitate with lead acetate, and a white precipitate, 
turning black on heating, with mercurous salts. To this 
substance they gave the name of toxicodcndric acid. 




Fig. 44. Rltus toxicodendron. 

Their results were confirmed in 1883 by Pettigrcw, who 
also found that the acid gave a red colour with ferric 
salts. 

The black stain produced by the juice of E. toxicodendron 

* Xatumal Dispensatory, p. 1382. 



198 INKS AND THEIE MANUFACTUKE 

cannot be removed by the treatment with alcohol or soap 
and water, but dissolves in ether. 

Rims Venenata. This is a shrub which grows on 
marshy ground in North America, where it is popularly 
known as the poison sumach. It is usually from 10 to 
15 feet high, but sometimes reaches a height of 30 feet. It 
has a dark grey bark, and produces greenish-white 
flowers and berries. 

On making an incision in the bark a thick white, 
opaque, pungent fluid exudes, which on exposure to the 
air rapidly becomes black. When this liquid is boiled 
with water the volatile constituents are expelled, and the 
residue can be used as a black varnish, similar to that 
prepared from the Ehus vernicia of Japan. 

The poisonous symptoms caused by the juice are 
similar to those produced by Ehus toxicodendron, but 
many persons are quite immune to its effects, whilst 
others are more affected by its emanations than by those 
of E. toxicodendron. 

The workmen who use it as a finishing varnish for boots 
frequently suffer from its action.* 

Rhus radicans is a variety of E. toxicodendron, and not 
a separate species. It produces round greenish-white 
berries, and its juice has similar properties. 

Other Vegetable Juices. Lewis in 1763 made 
numerous experiments to determine the permanency of 
the stains produced by the juices of different plants. He 
found that the milky juices of poppies, dandelion, hawk- 
weed and sowthistle gave brown or brownish-red 
characters, but that these were readily removable on 
washing the linen. 

The colourless juice from hop stalks, on the other hand, 
gave a very permanent pale reddish-brown stain. 

Sloe juice. The juice from sloes used by itself gave 
a pale brown stain, whilst with the juice used in conjunc- 
tion with alkali a much darker stain was produced. The 
fresh juice, on baking, became red, and when applied 
to linen gave red stains, which became blue on contact 
with soap. These characters were very permanent, and 
had only become faint after long continued washing. 
* Millspauch, American Medicinal Plants, p. 37. 



MARKING INKS 199 



CHEMICAL MARKING INKS. 

Silver Inks. Of the different substances that have been 
employed as marking inks, the best known and most com- 
monly used has been a solution of a silver salt, the reduc- 
tion of which within the fibres of the material has left an 
insoluble black deposit of a more or less permanent nature. 

The earliest inks of this type required the linen to be 
previously treated with what is known as a pounce and then 
dried, but these have been entirely superseded by inks 
which are reduced by passing a hot iron over the writing. 

An ink of this earlier type was recommended bylieimann* 
as late as the year 1870. It contained 1.6 parts of silver 
nitrate, 2 parts of gum arabic, J part of sap green in 16 
parts of water ; whilst the pounce consisted of 2 parts of 
crystalline sodium carbonate and 2 parts of gum in 8 parts 
of water. 

A similar ink intended for use with steel pens, , was also 
described by Reimann. It was prepared by dissolving 2 
parts of silver nitrate and 2\ parts of gum in 5 parts of 
ammonia solution and filtering the liquid, a little magenta 
red being added to impart a temporary colour. The pounce 
for this ink contained 3 parts of sodium carbonate with 
2 J parts of gum in 9 parts of water. 

Redwood's Marking Ink. This was prepared by adding 
a solution of 3 1 parts of silver nitrate in water to a solu- 
tion of 50 parts of sodium carbonate in water, collecting 
and washing the precipitated silver carbonate, triturating 
it with tartaric acid and adding sufficient ammonia solu- 
tion to dissolve the silver tartrate. The ink was then 
completed by the addition of 15 parts of archil extract, 16 
parts of white sugar, and 50 parts of gum arabic. With 
this ink no previous preparation of the fabric was neces- 
sary, a hot iron being passed over the writing to start the 
reduction. 

Some time afterwards Reade (Eng. Pat., No. 11,474; 

1846) claimed the use of a marking ink the basis of which 

was also silver tartrate. This was prepared by rubbing 

together in a mortar equal parts of tartaric acid and silver 

* Dingier s poly t. Journ., 1870, cxcv. 283. 



200 INKS AND THEIR MANUFACTUEE 

nitrate, then adding water, and finally neutralising the 
liquid with ammonia. In this process the somewhat tedious 
operation of washing the silver carbonate, as in Redwood's 
process, was dispensed with. 

Claim was also made for the addition to this ink of an 
ammoniacal solution of a gold salt, so as to render the 
writing proof against the action of solvents for silver salts. 

Dieterich (1897) recommends a solution of 25 parts of 
silver nitrate and 1 5 of gum in 60 parts of ammonia solu- 
tion, with the subsequent addition of 2 parts of lamp-black 
or indigo as a temporary colouring-matter. 

The ink is used with a quill pen, and the writing is fixed 
by passing a hot iron over it. By increasing the amount 
of gum to 25 parts, a rubber stamp can be used with the 
ink. 

Soubeiran's Marking Ink * consisted of 8 parts of silver 
nitrate, 4 parts of sodium carbonate, and 3 parts of copper 
nitrate, in 100 parts of ammonia solution. 

Bufton (Eng. Pat., No. 738 ; 1856, Prov.) claimed the 
addition of platinum chloride to a silver marking ink, 
with the object of rendering the characters more per- 
manent. 

Kindt's Marking Ink] consists of 1 1 parts of silver nitrate 
dissolved in 22 parts of ammonia solution and mixed with 
a solution of 22 parts of sodium carbonate in 12 parts of 
water. The ink is then thickened by the addition of 50 
parts of gum and coloured with 2 parts of sap green. Marks 
made with this ink on linen gradually darken on exposure 
to light, but the process of reduction is accelerated by 
heat. 

Silver Chloride Marking Ink. The linen fabric is first 
prepared with a 20 per cent, solution of sodium chloride, 
to which has been added 50 per cent, of gum arabic. The 
ink is prepared by dissolving i part of silver nitrate and 
2 parts of gum in 10 parts of water, and adding a little 
indigo carmine as temporary colouring-matter. The silver 
nitrate in the ink reacts with the sodium chloride in the 
prepared linen, forming silver chloride, which is reduced 
on exposure to sunlight. 

* Dingier'' s polyt. Juurn.. 1848, cviii. 157. 
f Ibid., 1859, cliii. 393. 



MARKING INKS 201 

Ruhr's Marking Ink* Very black characters are pro- 
duced by an ink consisting of i part of silver nitrate and 
6 parts of gum arabic in 6 parts of water, on linen pre- 
viously prepared with a solution of i part of sodium hypo- 
sulphite and 2 parts of gum in 16 parts of water. 

Gold Marking Inks. One of the best known gold inks 
is based on the formation of what is known as the purple 
of Cassius. The linen is prepared by treatment with a i 
per cent, solution of stannous chloride containing 10 per 
cent, of gum, whilst the ink consists of a i per cent, solu- 
tion of the double chloride of gold and sodium, to which 
also has been added 10 per cent, of gum. 

If the fabric be prepared with a 20 per cent, solution of 
oxalic acid containing 40 per cent, of gum, instead of with 
the tin solution, the gold writing has a metallic lustre after 
being ironed and washed. 

Gold marking ink is more permanent than silver ink, 
and its addition to the latter was patented by Beade 
(supra). 

Platinum Marking Inks. These are prepared in two 
solutions like the gold ink. The fabric is first treated with 
a mordant containing 30 parts of oxalic acid and 30 parts 
of gum in 100 of water and dried. The ink, which consists 
of i part of platinum chloride and 2 parts of gum in 10 
parts of water, produces red marks on the prepared linen, 
^yhich should be well washed as soon as the writing is dark 
enough. 

A purple platinum marking ink described by fteimann 
(Iqc. cit.) contains i part of platinum chloride in 16 parts 
of 'water. The linen is first prepared with a solution of 3 
parts of sodium carbonate and 3 parts of gum in 12 parts 
of water and dried. After the letters have been written 
on this prepared surface and have dried, the place is 
moistened with a solution of i part of tin chloride in 4 
parts of water, which changes the writing to reddish 
purple. 

Marking Inks containing other Metals.- In addition 
to platinum and gold salts, which have been used either 
alone or in conjunction with silver salts as constituents of 

* Dingier' s polyt. Journ., 1867, clxxxv. 326. 



202 INKS AND THEIR MANUFACTURE 

marking inks, and which are obviously too expensive for 
general use, numerous other metallic compounds have been 
employed for the same purpose. Thus in 1878 Hickisson 
(Eng. Pat., No. 5122) protected an ink containing a salt of 
vanadium with an oxidising agent composed of metals 
or salts preferably those of nickel and copper, to act as 
mordants. 

Sachs (Eng. Pat., No. 1838 ; 1880) has produced solu- 
tions which he claims to be good marking inks, by the 
action of polysulphides of heavy metals, such as those of 
iron, zinc, or copper, on organic substances, such as non- 
volatile fats or sawdust, in the presence of a suitable 
metallic hydroxide or sulphide, e.g., sodium hydroxide or 
sodium sulphide. 

Marking inks of various colours were protected by Lang- 
beck (Eng. Pat., No. 5946; 1882). These consisted of pig- 
ments, such as gas-black, vermilion, ultramarine, cadmium 
yellow, and emerald green, mixed with a suitable propor- 
tion of albumin, and incorporated with a liquid base com- 
posed of salicylic acid, turpentine oil, spirits of wine, 
glycerin, and water in approximately specified proportions. 

In a subsequent patent (No. 751 ; 1883) taken out by 
Hickisson and Langbeck, the basis of the ink made from 
these pigments was a solution of india-rubber in carbon 
bisulphide, a little essential oil being added to prevent too 
rapid evaporation. The fabric was heated after marking. 
In yet another method, protected by the same patentees 
(No. 752 ; 1883), the mixture of pigments and albumin was 
added to a base consisting of 5 to 8 grains of arsenic pent- 
oxide, 10 grains of turpentine oil, 6 drachms of glycerin, 
and i oz. of water. 

Dimitrys Bichromate Marking Ink (Eng. Pat., No. 648; 
1888) consists of a soluble colouring- matter mixed with 
gelatin and potassium bichromate, this last constituent 
being reduced on exposing the writing to the action of 
sunlight. 

Molyldic Marking Ink. An ink was recommended by 
Roder* in 1856 as adhering well to the linen, and resisting 
the action of both acids and alkalies. It was prepared by 

* Dingier' 1 s polyt. Jo-urn,, 1856, cxli. 159. 



MARKING INKS 203 

dissolving 5 parts of molybdic oxide in sufficient hydro- 
chloric acid, and adding 6 parts of gum arabic and 2 parts 
of sweetwood extract (Ladvrifae) in 30 parts of water. 
When the writing was dry the linen was treated with a 
solution of tin chloride. 

Copper Marking Inks. The precipitate obtained on 
treating a solution of copper chloride with potassium hy- 
droxide is dissolved in as little ammonia solution as possible, 
and a little dextrin or gum added as a thickening agent. 
The writing done with this ink becomes black when a hot 
iron is passed over it. 

Scoffem (Eng. Pat., No. 1744 ; 1859) protected a process 
of making an ink for marking cloth, paper, &c., by immers- 
ing organic fibrous material, such as silk, in ammonia 
solution containing copper, and admitting air through a 
small opening from time to time. The solution of silk in 
this "copperised ammonia '"' was described by the inventor 
as a " lustrous black ink." 

A Blue Indelible Ink recently described * consists of a 
mixture of a silver and a copper marking ink. (a) Silver 
nitrate 10 parts in 30 parts of ammonia solution, (b) 
Sodium carbonate 10 parts, gum arabic 15 parts, and copper 
sulphate 5 parts in 40 parts of water. The two parts () 
and (b) are mixed together. 

Manganese Marking Ink. Eeimann (loe. cit.) recom- 
mends the following as a cheap brown marking ink. The 
linen is first prepared by treatment with a solution of I 
part of a ferrocyanide and J part of gum in 3 parts of water 
and dried. The writing is then done with a solution of 4 
parts of manganous acetate in 12 parts of water, and the 
linen finally treated with a solution of 4 parts of potassium 
hydroxide in 10 parts of water. 

This causes the separation of manganese hydroxide, 
which is gradually oxidised, forming a dark brown manga- 
nese oxide. 

This process is manifestly too complicated for ordinary 
use, and the treatment of the linen with strong caustic 
alkali solution must have an injurious effect upon the fibres. 

Aniline Marking Inks. An ink in one solution is 
obtained by thoroughly mixing 2 parts of aniline black in 
* Solent. Amer. Suppl., June 31, 1902. 



204; INKS AND THEIR MANUFACTURE 

401 parts of strong alcohol (95 per cent.) containing 2 parts 
of hydrochloric acid, and adding a solution of 3 parts, of 
shellac in 150 parts of the strong alcohol. The writing 
done with this ink is not removed by water, but is not very 
resistant to the action of alkalies. 

Jacobsen's Aniline Ink.* This ink depends on the for- 
mation of aniline black within the fibres. 

It consists of two solutions, which are kept separate 
until just before use : 

; (a) Copper Solution. Copper chloride, 8.52 grins. : 
sodium chlorate, 10.65 g rmg - 5 and ammonium chloride, 
3.35 grms., in 60 c.c. of water. 

(b) Aniline Solution. Aniline hydrochloride, 20 grms., 
dissolved in 30 c.c. of water, and mixed with 20 grms. of 
a solution of gum arabic (1:2) and I grm. of glycerin. 

For use, I part of (a) is mixed with 4 parts of (&). The 
writing on linen first appears green, and then gradually 
becomes black on exposure to the air. The change takes, 
place at once on heating the fabric, but it is advisable to 
hold it over steam, since dry heat tends to render the 
marked places brittle. Finally the place should be washed 
in soapy water, which renders the writing blue-black. 
Marking properly done with, this ink resists the action of 
acids and alkalies, and can be frequently washed without - 
being rendered much fainter. 

Indigotin Marking Inks. The so-called indigo blue 
when pure is known in chemistry as indigotin (C 16 H 10 N 2 2 ). 
When this is treated with a reducing agent it is converted 
into a colourless compound, indigo white (C 16 H 12 N 2 2 ) r 
which is .readily soluble in solutions of alkalies, and has 
only to be exposed to the air to be gradually oxidised again 
into the insoluble blue compound. 

An indigo marking ink based on this reaction is prepared 
by treating, a mixture of 20 parts of indigo blue powder 
and 40 parts of ferrous sulphate with a solution of 40 parts 
of sodium hydroxide in 200 parts of water. The whole is 
then left for several days in a well-corked bottle, which is 
shaken from time to time until the reduction is complete, 
and all sign of blue has disappeared. The liquid is then 
decanted, and 20 parts of gum arabic added to i part 

* Dingier ' polyt. Jovrn.. 1867, clxxxiii. 78. 



MARKING INKS ; 205 

of a saturated solution of litmus to form the provisional 
colouring-matter. The writing done with this ink is soon 
oxidised by the atmospheric oxygen, and eventually 
becomes deep blue. The same oxidation gradually takes 
place in the ink, with the formation of a blue deposit in 
the bottle. 

A marking ink patented by Johnson (Eng. Pat., No. 1771 ; 
1880) is based on the synthetical formation of indigo blue 
within the fibres of the fabric. The material is treated 
with a solution containing ortho-nitro-phenyl-propiolic 
acid, a reducing agent such as glucose, and a fixed caustic 
or carbonated alkali. The writing is developed by the 
action of steam, which produces a blue colour, or by dry 
heat, which makes it black. 

Alizarine Marking Ink. A red marking ink, containing 
the pigment of madder (alizarine) as its basis, was patented 
by Moller in 1864 (Eng. Pat., No. 2511). The linen was 
first prepared by treatment with a solution of alum, and 
the marking done with an ink composed of an alcoholic 
extract of madder mixed with an alkali salt, gum, and 
vermilion. 

Examination of Marking Inks. The chief essentials 
of a good marking ink are : (i) It shall not injure the fibres 
of the fabric ; (2) it shall not be too viscous to flow 
smoothly from the pen, and yet not so fluid as to Ci run " 
when applied to the linen ; (3) it shall produce characters 
which rapidly darken when treated with a moderately hot 
iron or otherwise ; (4) the characters shall not fade when 
repeatedly washed with soap and water, and shall resist 
the action of acids, alkalies, and bleaching-powder. 

The composition of an ink is of subsidiary importance 
as compared with the results of practical tests. It is best 
to make characters both on linen and fine fabric, and to 
follow the manufacturer's directions for the subsequent 
treatment of the material. 

Marking Ink Pencils. The earliest pencils intended 
for marking linen contained a silver salt incorporated with 
a suitable basic material and a provisional colouring-matter. 
In Dunn's patent (Eng. Pat., No. 2316 ; 1858) plumbago is 
mentioned as a suitable substance to be mixed with the 
silver salts. 



206 INKS AND THEIR MANUFACTURE 

A similar pencil was patented by Schroll (Eng. Pat., No. 
379; 1877). This was composed of a suitable clay earth 
mixed with silver nitrate or other soluble silver salt, and 
plumbago freed from impurities that would cause reduction 
in the silver salt. 

In 1878 Hicldsson (Eng. Pat., No. 5122) adapted his 
vanadium marking ink (supra) to the preparation of mark- 
ing ink pencils, gum, gelatin, dextrin, clay, or other suitable 
substance being added, and the mass moulded into the 
required shape. 

Marking pencils giving different coloured characters 
were prepared by Hickisson and Langleck (Eng. Pat., No. 
752, 1883) from the marking inks containing a suitable 
pigment and albumin in a liquid base of arsenic pentoxide, 
turpentine oil, glycerin, and water. 

A silver pencil also patented by Hickisson (Eng. Pat., No. 
9149; 1884) has a marking-point which may consist 
of silver nitrate and potassium nitrate, or in some cases 
ammonium carbonate, fused with gum, whilst the other end 
of the pencil contains a mordant composed of, e.g., borax, 
wax, and pyrogallol, which is applied to the writing to fix 
it. In a subsequent patent (Eog. Pat., No. 15,961; 1884), 
claim is made for separate pencils containing only the mor- 
dant. Aniline dye-stuffs soluble in oil, claimed by Hickis- 
son (supra) are also made the colouring material in marking 
pencils. For this purpose they are incorporated with 
suitable ingredients, such as gum tragacanth, kaolin, and 
borax, into a solid mass. The linen fabric is damped with 
a suitable oil, such as castor oil, and the writing finally 
heated. 

In our experience with certain marking ink pencils of 
foreign origin containing aniline dye-stuffs, the writing is 
of a very fugitive character. 



CHAPTER XIV. 

SAFETY INKS AND PAPERS. 

CONTENTS. Various safety inks Kesinous inks Train's 
carbon gluten ink Soluble glass ink Other carbon inks 
Safety papers -with special inks Patent permanent 
inks Patent safety papers. 

THE term "safety" has been frequently applied to inks 
which are supposed to resist the action of all chemical 
agents not sufficiently powerful to destroy the paper or 
parchment itself. The importance of such an ink in the 
case of historical records or legal documents, &c., is obvious, 
and numerous experiments have been made to discover the 
best fluid for the purpose. 

It has already been noted in the introduction that iron 
gall inks may, under favourable conditions, almost equal 
carbon inks in def} T ing the ravages of time, although many 
instances can be cited where inks of the same character 
have prematurely faded. It may be pointed out in con- 
nection with this imperfection that chlorine is used, as a 
bleaching agent in paper manufacture, and although 
"antichlor" (sodium thiosulphate) is used to remove free 
chlorine, cases may occur in which a trace of the chlorine 
is left, and would then have an effect upon an iron ink. 

Various Safety Inks. Several of the earlier formulas 
for producing permanent writing fluids have already been 
described in chap. i. } in the section dealing with carbon 
inks, p. 34. 

Inks recommended by French Commission. In 1831 Or 
Commission appointed by the Paris Academie des Sciences, 
and including such eminent chemists as Gay-Lussac and 
Chevreul, made a critical examination of all the inks that 
had been proposed up to that time for the prevention of 



208 INKS AND THEIR MANUFACTURE 

the falsification of writing, and concluded that prior to 
1826 none was satisfactory. They were either too thick, 
or attacked the paper, or yielded a deposit too readily. Of 
the different inks submitted, the Commission recommended 
the two following : 

i. Indian ink (4 to 5 grms.) mixed with 1000 grms, of 
dilute hydrochloric acid (2.010 sp. gr.). This ink flowed 
well and had good .penetrating power, whilst the acid did 
not injure the paper. 

ii. A solution of manganese acetate (sp. gr. 1.074). With 
a ninth of its volume of acetic acid (100 parts neutralising 
1 60 of sodium carbonate), thoroughly incorporated with 
Indian ink. The writing was then fixed and rendered 
indelible by holding it over ammonia vapour. 

The advantage of this ink over the preceding one is that 
the paper will not contain free acid. 

We have prepared carbon inks from these formulae, and 
find that the writing resists the action of water, acids, and 
bleaching agents. In the case of the first ink, however, 
we find the quantity of Indian ink mentioned quite insuf- 
ficient. We used the finest that we could obtain, and had 
to add at least six times as much in order to obtain cha- 
racters of sufficient blackness. After the treatment with 
ammonia vapour the writing becomes much greyer. 

MacCullock* used a solution of potash and wood tar, 
whilst Thomson^ mixed lamp-black with a solution of 
shellac and borax. 

Resinous Inks. This last ink is very much on the lines 
of that described by Dcsmarcst,^ viz., shellac, 15; borax, 
8; gum arabic, 8; lamp-black, 10; and water, 130 parts. 

The powdered shellac and borax are boiled with the 
water, and the solution mixed with the powdered gum and 
lamp-black, and eventually decanted from the heavier 
particles. 

In 1837 H. Stephens and E. Nash patented (Eng. Pat., 
No. 7342) the addition of carbonaceous matter to saline or 
alkaline solutions of resinous substances to form compounds 
not attacked by ordinary chemical agents (vide infra). 

* Ann. de Chim. et Phys.. 1831, xlviii. 5. 

t IMd. 

j Les Encre* et Ciniges, 1895, p. 141. 



SAFETY INKS AND PAPERS 209 

An ink of this character is prepared by boiling 10 parts 
of ordinary rosin and 10 parts of sodium, potassium, or 
ammonium carbonate, either alone or, preferably, mixed 
in equal proportions, with 100 parts of water, and adding* 
a mixture of 4 parts of powdered gum, and 2 parts of 
lamp-black. 

Traill's Carbon Gluten Ink.* This consisted of lamp- 
black and indigo incorporated with an acetic acid solution 
of the gluten of wheat flour. The gluten was prepared by 
kneading the flour in a current of water until the starch 
has been separated. After twenty-four to thirty-six hours 
in the water it was digested with acetic acid (sp. gr. 1.033 
to 1.034) in the proportion of 20 to 3 of gluten. The grey 
liquid eventually obtained with the aid of gentle heat was 
then used as the medium for the pigment, which consisted 
of about 2 per cent, of purified lamp-black, and about J 
per cent, of indigo. 

An ink attributed to Herberger is essentially identical 
with that devised by Traill. 

Traill states that his ink was at once adopted (1840) by 
the National Bank of Scotland, which had recently been 
the victim of numerous forgeries, in which the ink on bills, 
&c., had been erased and other figures substituted. As a 
matter of interest we made inquiries from the present 
authorities of that bank in Edinburgh, who have kindly 
informed us that they have no record of any other ink than 
ordinary iron gall ink having been used by them. It is 
not improbable that the use of Traill's carbon ink was dis- 
carded on the introduction of cheques printed with special 
inks, which would change colour if any chemical were used 
to remove the writing. 

,:.. Baudrimont's Soluble Glass Ink.f This is an inti- 
mate mixture of soluble glass (sodium silicate) with 10 
per cent, of lamp-black. The silica, on separating from 
the ink during the drying, encloses particles of carbon, 
thus rendering the characters permanent. It is advan- 
tageous to remove the sodium carbonate formed by the 
action of the carbon dioxide in the air upon the sodium 

* Trans. Boy. Soc. Edin., 1840, xiv. 426. 
f Desmarest, Les Encres et Cirages, p. 144. 

O 



210 INKS AND THEIR MANUFACTURE 

oxide by first treating the written paper with dilute acetic 
acid, and then thoroughly washing it with water. 

We have found that the ink thus prepared from com- 
mercial sodium silicate is much too thick for use, and 
requires to be suitably diluted with water. Ink having a 
specific gravity of 1.270 flows freely from the pen and 
gives very black writing. When the dried characters are 
treated with water the surface ink is readily washed off, 
but there still remains a greyish writing within the fibres 
of the paper, and this is not removed by leaving it in 
water for twenty-four hours. If the writing be left for 
twelve hours before immersion in water much less of the 
pigment is removed. The ink can be blotted immediately 
after writing without rendering it too pale. It is not 
affected by acids, alkalies, or chlorine. 

Other Carbon Inks. Numerous other formulas have 
been given for the preparation of inks of this character, 
but most of them are only later modifications of those 
described above. Thus, a weak solution of sodium 
hydroxide is used instead of hydrochloric acid as a 
medium for Indian ink (Beza/nger) ; and another ink con- 
sists of lamp-black and gum arabic incorporated with a 
dilute solution of oxalic acid. 

This latter ink has not much penetrating power, and the 
writing can be removed from the paper by careful washing 
with water. 

Whitfield (Eng. Pat., No. 7474; 1837) prepared lamp- 
black from a mixture of linseed oil, Venice turpentine, 
and other organic substances, by firing the mass with a 
hot iron, and collecting the soot in an inverted cone. I Ib. 
of this lamp-black was mixed with i quart of vinegar 
2 galls, of hot water, J Ib. of gum, and J Ib. of shellac, 
and the whole boiled for ten minutes. Powdered galls 
(i Ib.) and logwood chips (2 Ibs.) were then introduced, 
and the ink stirred until cold, and exposed for three weeks 
to the atmosphere in flat pans. 

Safety Papers used with Special Inks. Traill (loc. 
cit.), in the course of his experiments, tested the per- 
manency of the writing produced by different solutions of 
metallic salts on specially prepared papers. Sheets of 
unsized paper were soaked in the following different 






SAFETY INKS AND PAPERS 211 

solutions, and then dried : (i) An infusion of galls ; (ii) a 
solution of potassium ferrocyanide ; (iii) sodium chloride 
solution ; (iv) sodium phosphate solution ; (v) potassium 
iodide solution ; and (vi) potassium bichromate solution. 

i. Characters on this paper made with iron sulphate or 
copper sulphate were readily removed by chlorine, oxalic 
acid, &c. 

ii. Ferrocyanide Paper. Antimony chloride solution 
gave bright blue characters, which resisted the action of 
chlorine, but were effaced by ammonia. Iron sulphate 
gave dark-blue writing, copper sulphate brown characters, 
and cobalt nitrate deep-brown characters, which resisted 
the action of alkalies, but were bleached by chlorine. 

iii. Sodium Chloride Paper. The characters produced by 
silver nitrate on this paper were removed by ammonia. 

iv. Sodium Phosphate Paper. Acetate of lead produced 
intense yellow characters. 

v. Metallic iodides formed in the paper were equally 
unreliable, as was also the case with chromates. 

vi. Metallic sulphides, whether precipitated in the paper 
or added in the form of coloured compounds (lead sul- 
phide), to ordinary inks, were easily bleached by chlorine. 

Indigo sulphate was also bleached by chlorine, but 
when added to an ordinary iron gall ink increased its 
stability. 

Antimony and Cobalt Salts Mixed. A mixture of cobalt 
nitrate and antimony chloride ground together and mixed 
with gum water yielded an ink which gave dark-brown char- 
acters on ferrocyanide paper. The writing was weakened, 
but not destroyed, by acid or alkali ; but when soaked 
alternately in these reagents was completely effaced. 

Summarising the behaviour of different reagents on the 
metallic compounds tried, Traill came to the following 
conclusions : (i) Chlorine bleached all with the exception of 
the blue precipitate formed on adding antimony chloride 
to potassium ferrocyanide. (ii) Oxalic acid completely 
bleached gall ink, Prussian blue, lead iodide, mercury 
iodide, lead chromate, and indigo sulphate, though the 
last offered more resistance, (iii) Antimony chloride 
weakened or destroyed all the metallic characters with 
the exception of the antimony ink. Indigo, again,, offered 



212 INKS AND THEIR MANUFACTURE 

considerable resistance, (iv) Caustic alkalies destroyed all 
with the exception of the salt formed by adding cobalt 
nitrate to potassium ferrocyanide. 

Patent Permanent Inks. The addition of finely divided 
carbon to ordinary writing inks has been claimed in 
numerous patents ; e.g., by Scott in Eng. Pat., No. 8770, 
of 1840, who added gas-black, indigo and Prussian blue 
to gall and logwood ink. In Heade's patent, No, 11,474, 
of 1846, the use of Prussian blue was also claimed. 

An indelible ink patented by Stephens and Nash in 1837 
(Eng. Pat., No. 7342) was prepared by distributing the 
carbon in a solution of a resinous soap ; whilst Melville 
(Eng. Pat. 534 ; 1860) claimed an ink consisting of plum- 
bago, with resin, gum, alum, and a suitable colouring- 
matter. In 1861 Stevens (Eiig. Pat. 2972) patented an 
indelible anti-corrosive ink which consisted of solutions of 
aniline dyes mixed with finely divided carbon. The ink 
protected by Gaffard (Eng. Pat., No. 1839 ; 1874) was com- 
posed of a mixture of carbon with the solution of an 
alkali silicate. 

A mixture of sugar, aniline black, and soot in logwood 
extract form the constituents of Fonsecas patent ink (Eng. 
Pat., No. 859; 1883); whilst JTass(Eng. Pat., No. 9249: 
1885) employs carbonised sugar scum as the source of the 
carbon. A solution of soap in water or other medium is 
claimed by Lichtentag (Eng. Pat., No. 24,644; 1898) as 
the liquid part of a carbon ink. 

Only a few inks of this class not containing carbon have 
been patented. Ellis (Eng. Pat., No. 2267 ; 1865) claimed 
that an indelible ink was produced by precipitating col- 
ouring-matters by means of silicic acid, and dissolving the 
precipitate in a suitable silicate solution. In 1891 Leech 
and Harrobin (Eng. Pat., No. 1616) protected a writing 
fluid consisting of turpentine, asphalt, resin, alum, bees- 
wax, and colouring-matter. 

Aluminium powder with a protective varnish forms the 
basis of Blancan's indelible ink (Eng. Pat., No. 7263 ; 



Patent Safety Papers. ^One of the earliest so-called 
" safety" papers was that described by Stevenson (Bu 
Pat., No. 7313 ; 1837). This consisted of paper impreg- 



SAFETY INKS AND PAPERS 213 

nated with a solution of manganese chloride and potassium 
f errocyanide, and was stated to be stained by any chemical 
that would remove ink. 

Ballande's safety paper was impregnated with mercuric 
chloride, or a salt of iron or copper, whilst the ink con- 
sisted of a solution of sodium thiosulphate with alum, or 
alkali or alkaline salts, or of other salts (e.g., iodides, sulpho- 
cyanides, &c.) capable of forming coloured insoluble com- 
pounds within the paper. (Eng. Pats., No. 861, 1859; 
and 388, 1860). 

In 1864 Baildon (Eng. Pat., No. 2223) claimed the use 
of a safety paper from which the colour was discharged 
by acid in the special ink to be used. A patent on similar 
lines (No. 6938) was published by Thackerin 1895, the 
paper in this case being coated with colour, which was 
removed as soon as it came in contact with the ink. 

It is interesting to note that the colour of ordinary blue 
paper such as is used for official and commercial purposes 
is discharged by dilute mineral acid ; and we have good 
authority for stating that acid was actually in use as a 
white ink on that kind of paper some years before the 
date of Baildon 's patent. 



CHAPTER XV. 

SYMPATHETIC INKS. 

CONTENTS. History Various sympathetic inks Patent 
sympathetic inks. 

History. 

THE term sympathetic ink is applied to writing fluids 
which yield characters that remain invisible until heated 
or treated with some suitable reagent. Such inks appear 
to have been known in the early days of the Roman 
Empire, for Ovid mentions milk as a suitable liquid, whilst 
Pliny refers to the juice of different plants. 

The earliest known chemical sympathetic inks were re- 
garded as acting by magnetism. Thus Brossonius, writing 
in a medical treatise in the early part of the seventeenth 
century, describes a " magnetic fluid " made from " arseni- 
ated liver of sulphur," and only visible when looked at with 
" eyes of affection." This appears to have been nothing 
more than an ink of lead agatate, the characters being 
rendered visible by the action of 



Borel * also describes these inks, the secret of which he 
learnt from Brossonius, as aquce magnetice e longinquo 
agentes, but points out that there is nothing miraculous in 
their action. They are also alluded to by Otto Tachcn 
(1669), who denied that there was anything magnetic in 
their action, and by numerous later writers. 

The name sympathetic appears to have been first used by 
Le Mort to describe the lead acetate ink, and the term was 
subsequently applied to all secret inks of the same kind. 

In 1715 Waiz discovered the use of solutions of cobalt 
salts as sympathetic inks, and the French chemist Hellot 
also gave a description of them a few years later. 

* Historiarum Centuriae, iv. p. no. 



SYMPATHETIC INKS 



215 



Various Sympathetic Inks. The change in the colour 
of characters written with a solution of cobalt chloride is 
due to the fact that the pink salt loses part of its water of 
crystallisation when heated to 120 C., forming a blue 
compound, and that the latter on exposure to the air 
gradually absorbs water, and regains the pink colour 
which is nearly invisible on white paper. By the addition 
of other salts to the cobalt solution e.g., nickel sulphate 
the colour of the heated characters is modified. 

Cobalt sulphocyanide solutions give pale red writing, 
which changes to blue on heating. 

The following table gives a list of some of the better 
known substances used as sympathetic inks : 



Colour. 


Ink. 


Mordaiit. 


Black or brown. 


Lead acetate. 
Mercuric chloride. 
Galls. 
Pyrogallol. 
JSilyer salt. 


Hydrogen sulphide. 
Stannous chloride.*-^' 
Iron sulphate. 
An alkali. 
(Action of light). 


Blue. 


Starch. 
Cobalt nitrate. 
Iron sulphate. 


Iodine. ^ 
Oxalic acid. 
Potassium ferrocyanide. 


Yellow. 


Copper chloride. 
Basic lead acetate. 
Antimony chloride. 


(Yellow on heating). 
Hydriodic acid. 
Galls. 


Green. 


Cobalt chloride with a 
nickel salt. 
Potassium arsenate. 


(Action of heat). 
Copper nitrate, i/ 


Purple. 


Gold chloride. 


Stannous chloride. 


Gold. 


Gold sodium chloride. 


Oxalic acid (10 per cent.) 
On treating with hot 
iron metallic lustre 
is produced. 



216 INKS AND THEIR MANUFACTURE 

A sympathetic method might be based on a process 
familiar to photographers, by which so-called " magic 
pictures " have been produced. A photographic print on 
bromide paper after being bleached in a solution of 
mercuric chloride and thus rendered invisible, is again 
made apparent by being placed in contact with blotting 
paper moistened with a solution of sodium thiosulphate 
{''hypo"). It is obvious that writing executed with any 
suitable developer on bromide paper would appear and 
disappear under similar conditions. 

Another method is suggested by the fluorescence of a 
solution of a quinine salt under ultra-violet light, or of 
other compounds under the influence of radium, X-rays, 
<fec. 

Sympathetic inks have frequently been put to an 
ingenious and perverted use by sharpers of the racecourse, 
two of whom were recently convicted of this kind of 
fraud. A betting paper giving the names of horses, &c., 
is' written in two kinds of ink, one of which fades away, 
whilst the other gradually appears. The disappearing 
ink commonly used is a weak solution of starch tinged 
with a little tincture of iodine, and writing done with 
this soon fades away, whether exposed to the light or 
not. 

The ink used for the invisible writing is often an 
ammoniacal solution of silver nitrate, which gradually 
darkens under the influence of light. Fugitive dyes have 
also been used as disappearing inks, such as e.g., quinoline 
blue and furfur-aniline, the solution of which gives 
magenta writing, which soon fades away under the influ- 
ence of sunlight. 

Patent Sympathetic Inks. Although sympathetic inks 
are usually regarded as only scientific toys, they have been 
applied to several practical purposes, and have been made 
the subject of different patents. 

In the Eng. Pat., No. 2389 of 1877, Kromer describes 
a process for detecting any tampering with envelopes, 
which consists of separating the two constituents of a 
sympathetic ink by the adhesive gum, so that should 
steam be applied to open the envelope the two substances 
come in contact and form an ink ; leaving a stain upon 



SYMPATHETIC INKS 217 

the paper. A similar device was patented by Pulford 
(Eng. Pat., No. 15565 ; 1889). 

Claim is made for the use of bichromate solution in Eng. 
Pat., No. 3657 of 1 88 1, the characters being made visible 
by the action of light. 

Quclch (Eng. Pat., No. 7472; 1888) has protected a 
method of writing with a saturated solution of potassium 
nitrate on a non-glazed surface, a part of the writing being 
afterwards touched with a red-hot wire. Papers thus 
treated are sold as toys for children. 

A sympathetic ink claimed by Himly (Eng. Pat., No. 
730; 1887) consists of a solution of platinum magnesium 
cyanide with a suitable medium, such as gum, gelatin, &c. 
When exposed to damp air this changes to pink, the colour 
disappearing on applying heat. 

An invisible ink claimed by Tschofcn (Eng. Pat., No. 
2130; 1890) consists of a mixture of chalk or similar 
substance with water, which is used for writing on a 
glazed surface, the characters being subsequently dusted 
over with graphite, bronze powder, &c., to render them 
visible. 

Adams (Eng. Pat., No. 3459 ; 1896) has patented the use 
of dilute sulphuric acid (i : 17) as an invisible ink, the 
writing being rendered permanently visible on heating the 
paper so as to bring about surface carbonisation. 

Another sympathetic ink which only becomes visible on 
heating the paper is described by Moller in Eng. Pat., No. 
21,991 ; 1897. It consists of about IOO parts of alum and 
100 parts of white garlic juice. The writing is rendered 
visible by heating the paper and cannot be removed by 
water. 

In Krctsclimami s patent (No. 6727, 1899) paper is 
treated with a solution of cobalt chloride, and a solution of 
rock-salt used as ink. Ou heating the paper the writing 
appears in pale green characters. In order to detect 
tampering certain signs are made on the paper with a 
solution of resorcin and paratoluidine, and these on heating 
change from red or yellow and become permanently black 
or brown. In a subsequent patent (No. 7367 ; 1900) 
Kretschmann has claimed a process of treating paper 
with a non-hygroscopic salt of cobalt (such as the basic 



218 INKS AND THEIR MANUFACTURE 

carbonate), and writing on it with a solution of salt and a 
substance such as vinegar, which will convert the salt in 
the paper into a hygroscopic salt. 

The sympathetic process described by Bachem (Eng. Pat. , 
No. 8976 ; 1899) consists of the use of two substances, such 
as cobalt chloride and magnesium platino-cyanide, in two 
layers, one of which becomes visible on heating, whilst the 
other simultaneously disappears. 



CHAPTER XVI. 

INKS FOR MISCELLANEOUS PURPOSES. 

CONTENTS. Ink powders and tablets Logwood ink 
powders Aniline ink powders Patent ink powders and dried 
inks Stencil inks Show card ink Inks for rubber 
stamps Inks for writing on glass Hydrofluoric inks 
Resin inks Foertsch's pencil for glass Inks for writing 
on metals Ink for writing on leather Ink for ivory 
surfaces Ink for writing on wood Fireproof inks. 

INK POWDERS AND TABLETS. 

THE earliest methods of preparing a powder which would 
yield an ink on the addition of water consisted of mixing 
together the finely-powdered ingredients of the ink. Thus 
Canneparius * in 1660 describes an ink powder containing 
equal parts of finely powdered galls and ferrous sulphate, 
with a sufficient quantity of gum and shellac. Obviously, 
ink thus prepared would be very pale and of poor quality. 

A later method was to evaporate a good iron gall ink 
to dryness, and to mix the powdered residue with water as 
required. The disadvantage of this process is that the 
pigment is rendered insoluble by the evaporation, and that 
the ink prepared again from the powder contains particles 
suspended in water instead of being in solution. This 
objection also applies to Leonhardi's f ink tablets, which 
were prepared in a similar fashion. 

Dietcrieh uses his oxidised tannin extract (p. 96) as 
the basis of portable gall ink powders. 

Logwood. Ink Powders. An old Austrian patent taken 
out by Platzerl claimed the use of a powdered ink, con- 

* De Atramentis, 1660, p. 273. 

f Dingier 'spolyt. Journ., 1856, cxlii. 446. 

J Ibid., 1859, cliv. 158. 



220 INKS AND THEIR MANUFACTURE 

sisting of 100 parts of logwood extract with i part of 
potassium bichromate and 10 parts of sodium sulphindigo- 
tate. 

Cooley (Eng. Pat., No. 106 ; 1867) made claim for ink 
powders yielding ink of different shades and containing 
logwood extract or hsematoxylin with various salts. Thus 
powdered logwood extract with potassium chromate and 
bichromate yields an ink of different shades of brown, 
whilst by adding potassium carbonate to the chromate a 
rich blue-black ink is produced, the colour being further 
modified by the addition of alum. The use of copper 
acetate in place of alum gives a blue-black shade ; whilst by 
using tin chloride, chrome alum or manganese sulphate in 
place of potassium chromate various shades of purple are 
produced. 

Dieterick* gives the following directions for making 
logwood ink powders : 

Red Logwood Ink. Logwood extract, 100 ; aluminium 
sulphate, 40 ; potassium oxalate, 40 ; potassium bichro- 
mate, 3 ; and salicylic acid, 1*5 parts, in I litre of water. 

Violet Logwood Ink. Logwood extract, 100 ; aluminium 
sulphate, 40 ; potassium oxalate, 60 ; potassium bisulphate, 
10; potassium chromate, 5-; and salicylic acid, 1.5 parts. 

Aniline Ink Powders. Owing to*the readiness with 
which they dissolve in water, certain aniline dye-stuffs 
are particularly suitable for the purpose .of ink powders. 

Viedt in 1875 recommended the use of nigrosine, which 
was to be dissolved before use in 80 parts of water ; and 
since then aniline dye-stuffs have formed the basis of 
numerous English patents (vide infra). 

Dieterich (loc. tit.) has also described ink powders of 
different colours prepared from aniline dye-stuffs : 

*fttack Ink Powder. Aniline green D., 9 ; Ponceau 
R.R., 8.0 ; phenol blue, i. 

Eed Ink Powder. Ponceau red, R.R. 

Green Ink Potcder. Aniline green. 

Violet Ink Powder. Phenol blue, 1.5 ; Ponceau R.R., 
2.0 parts. 

Blue-green. Phenol, blue 1.5 ; aniline green, 2.5 parts. 

* loc. cit. 



INKS FOR MISCELLANEOUS PURPOSES 221 

For copying ink powders greater proportions of colour- 
ing-matters to water must be used and sugar added, e.g. : 

Violet Copying Ink Powder. Methyl violet, 20 ; sugar. 
IO ; and oxalic acid, 2 parts. 

lied Copying Ink Powder. Eosine, 15 ; and sugar, 30 
parts. 

Blue Copying Ink Powder. Resorcin blue, 5 ; sugar, 
20 ; and oxalic acid, i.o parts. 

Patent Ink Powders and Dried Inks. The earliest 
patent for an ink powder was taken out by Holman in 
1668 (No. 258), but no details of the method of preparing 
the substance are given. After that date no patent seems 
to have been applied for until 1867, when Cooley (Eng. Pat., 
No. 106) claimed the use of various dry extracts of dye- 
stuffs and salts, such as extract of Brazil wood with salts 
of tin, alum, tartrate, alkali or acid ; Prussian blue, 
soluble indigo with suitable mordant ; sap green, with or 
without alum ; saffron with alkali carbonate ; extract of 
French, berries with alum ; and powdered galls or pyro- 
gallol or a mixture of these with ferrous sulphate. 

By ford's Ink Powder (Eng. Pat., No. 974; 1876) contained 
logwood extract, indigo sulphate, and ferrous sulphate. 

In 1878 Jacobsohn (Emg. Pat., No. 1 5 86, Prov.) described 
an ink powder for copying, which consisted of a solution of 
an aniline dye-stuff, with sugar, gum arabic, and glucose 
evaporated to dryness. 

Payne's tablet for inking rubber stamps (Eng. Pat., No. 
3179 ; 1886) consists of glycerin, gelatin, or other glutinous 
substance, with an aniline or other dye-stuff. An ink in dry 
form protected by Ashton (Eng. Pat., No. 14,388; 1889) 
is prepared by drying a solution of a soluble colouring 
containing gum, &c., on wood shaving, gelatin, &c. ; and 
similar patents were granted to Nienstadt and Goldma+m 
1894 f r the process of coating granules of non-porous 
material with a pigment and binding material (Nos. 3236 
and 5078). The ink claimed by Spencer (Eng. Pat., No. 
21,830 ; 1897) consists of an aniline dye-stuff mixed with 
sodium bicarbonate and a dry acid, the object of the latter 
being to cause effervescence and thus distribute the pig- 
ment through the water. 



222 INKS AND THEIE MANUFACTURE 



STENCIL INKS. 

Inks intended for use with stencil plates require to be 
fairly fluid, and to yield characters which dry rapidly, and 
are not easily effaced. 

Bine Stencil Ink. A mixture of 2 parts of shellac and 
2 parts of borax is boiled with water (say 25 parts), and 
the solution mixed with a sufficient quantity of ultra- 
marine to give the desired colour. 

Black Stencil Inks. (i) The shellac and borax solution 
described above is mixed with a suitable proportion of 
lamp-black or nigrosine instead of ultramarine. 

(ii) A mixture of 2 parts of manganese sulphate with 
I part of lamp-black and 4 parts of sugar is ground to a 
paste with a small quantity of water, and a little gum 
Arabic added to give consistency. 

Show Card Ink. An ink of similar character to the 
preceding inks has been recommended for marking show 
cards and tickets for shop windows. It consists of 16 parts 
of asphaltum, 18 parts of Venice turpentine, 4 parts of 
lamp-black, and 40 parts of turpentine oil, thoroughly 
mixed together. 

INKS FOE RUBBER STAMPS. 

Many of the inks used with rubber stamps consist of an 
aniline dye-stuff in a suitable fluid medium. 

Black Ink. This can be prepared from aniline black -J, 
alcohol 15, and glycerin 15 parts. It is poured upon 
the cushion of the stamp, and rubbed with a brush. 

Blue Ink. Soluble aniline blue, 3; distilled water, 10 ; 
acetic acid, 10 ; alcohol, 10 ; and glycerin, 70 parts. The 
blue is mixed with the water in a mortar, the glycerin 
then gradually added, and lastly the other ingredients. 

Inks of other colours are prepared in the same way, other 
dye-stuffs being used in place of the blue. For example, 
methyl violet, 3 parts ; fuchsine, 2 parts ; methyl green, 
4 parts ; nigrosine (blue black), 4 parts, &c. 

A bright red ink can be obtained by using eosine, but in 
this case the acetic acid must be omitted. 



INKS FOR MISCELLANEOUS PURPOSES 223 

Reissig's Cancelling Ink. An indelible ink intended for 
use with rubber stamps has been devised by Eeissig. It 
consists of the following ingredients : linseed oil varnish, 
16; fine lamp-black, 6; and ferric chloride, 2 to 5 parts. 
This ink must not be used with metal stamps. 



INKS FOR WRITING ON GLASS. 

Hydrofluoric Inks. One of the simplest fluids used 
for marking glass is a dilute solution of hydrofluoric acid, 
which reacts with the silica in the glass, forming a per- 
manent etching. 

The objections to the use of free hydrofluoric acid are 
that it is unpleasant to handle, and that it must be kept in 
a bottle composed of material e.g., gutta-percha upon 
which it does not act. 

It is far better to use a solution of a fluoride which is 
only mixed with an acid solution when required, as in the 
case of the following preparation : 

Solution I. Sodium fluoride, 36 parts ; potassium sul- 
phate, 7 parts ; distilled water, 500 parts. 

Solution II. Zinc chloride, 14 parts ; hydrochloric acid, 
65 parts ; water, 500 parts. 

Equal parts of the two solutions are mixed, and the 
writing done with a clean quill pen. The etching in the 
glass appears after about thirty minutes. 

Resin Inks. An ink which gives writing not removed 
from glass by water is prepared by mixing together the 
following substances : Turpentine, 15 ; shellac, 10; Venice 
turpentine, 3 : and lamp-black, 3 parts. 

Another formula for a fluid for writing on glass is as 
follows: Rosin, 20; alcohol, 150; borax, 35; methylene 
blue, I ; and water, 250 parts. 

Foertsch's Pencil for Glass. Eight parts of white 
wax are fused with 2 parts of tallow, and a pigment such 
as lamp-black or Prussian blue stirred in while the 
mixture cools. When nearly cold, it is rolled into pencil 
form on a slab, and covered with a paper case. 



224 INKS AND THEIR MANUFACTURE 



INKS FOR WRITING ON METALS. 

Inks for Metals in General. A black ink which cau be 
used for writing on clean metallic surfaces is obtained by 
fusing 5 parts of copal, then cautiously adding 6 parts of 
turpentine oil, little by little, and finally stirring i part 
of lamp-black into the mixture. 

For a red ink J part of cinnabar is used in place of the 
lamp-black, whilst inks of other colours can be prepared 
by the use of suitable proportions of pigments, such as 
Prussian blue, aniline dye-stuffs, &c. 

These inks should be thinned with turpentine oil to the 
required degree of consistency. 

Ink for Zinc Labels. An ink intended for writing on 
the zinc labels attached to plants was devised by Puscher.* 
It consists of i part of potassium chlorate and i part of 
copper sulphate, dissolved in 18 parts of water, and 
thickened with a little gum arabic. The writing is black, 
and will resist a fairly high temperature. 

A blue ink for the same purpose is obtained by dissolv-' 
ing 60 parts of potassium chloride and 1 20 parts of copper 
sulphate in 1400 parts of water, and mixing the solution 
with a solution containing i part of soluble aniline blue, 
and 100 parts of dilute acetic acid in 400 parts of 
water. 

Black Ink for Iron, Zinc, or Brass. A dull black writing 
is produced on these metals by an ink of the following 
composition : Copper sulphate, 5 ; dilute (5 per cent.) 
acetic acid, i ; gum, 2 ; and lamp-black i part, mixed 
with 5 parts of water. 

Ink for Copper or Tin. For these metals the ink 
described in the preceding paragraph must be modified 
thus : Copper sulphate, 5 parts ; ammonium chloride, 
3 parts ; hydrochloric acid, 3 parts ; gum, 2 parts ; and 
lamp-black I part, in 5 parts of water. 

Ink for Silver. Yellowish-brown characters are pro- 
duced on silver by a 7 per cent, solution of the double 
chloride of gold and sodium, and the colour is changed to 

* Wag-net* s Jahresber., 1873, xix. 206. 



INKS FOR MISCELLANEOUS PURPOSES 225 

black on exposure to the action of light. A solution of 
platinum chloride can also be employed as a black ink for 
writing on silver. 

INK FOR WRITING ON LEATHER. 

The leather is first treated with a 10 per cent, solution 
of gallotannic acid, containing i per cent, of gum arabic, 
and then dried. It can then be written on with an iron 
ink of the following composition : Ferrous sulphate, 2 ; 
gum, 3 ; and water 20 parts, to which a little indigo 
carmine is added to give a temporary colour, pending the 
formation of the iron gallotannate in the leather. 

INK FOR IVORY SURFACES. 

Lenher* recommends the use of solutions of silver 
nitrate ranging in strength from 10 to i percent., accord- 
ing to the depth of tint required. The ivory is prepared 
by being immersed in a strong solution of ammonia, and 
washed with water. The writing may be toned to a brown 
colour by treatment with a i per cent, solution of sodium 
gold chloride, and fixed in a 10 per cent, solution of 
sodium thiosulphate (hypo). 

INK FOR WRITING ON WOOD. | 

The surface of the wood is repeatedly brushed with a 
boiling solution of gelatin, and then sponged with a 
mordant containing 10 parts of alum, 2 parts of hydro- 
chloric acid, and 10 parts of tin chloride in 50 parts of 
water. Writing of different colours may then be done on 
this prepared surface with solutions of various pigments, 
such as cochineal (red), decoction of Persian berries 
(yellow), decoction of anacardium seeds (black), potassium 
permanganate (brown), decoction of logwood (blue), &c. 

FIREPROOF INKS. 

Numerous inks have been described which, when used 
with a specially prepared paper, produce writing that 

* Die Tinten Fabrikaiion, p. 228. t IMd. 

P 



226 INKS AND THEIE MANUFACTURE 

resists the action of fire. Speaking generally, these con- 
tain some incombustible material, such as graphite or a 
metallic compound, which leaves a residue of oxide or 
metal when heated, and are used with a paper containing 
more or less asbestos fibre. 

The use of such paper with a plumbago ink was claimed 
by Halfpenny in 1873 (Eng. Pat., No. 262), whilst Hyatt 
(Eng. Pat., No. 3684; 1873) also claimed the addition of 
asbestos to the raw material of paper. 

In 1 88 1 Meiht patented (Eng. Pat., No. 3410) fireproof 
inks for writing or printing on paper containing asbestos 
and wood fibre. These inks contained 5 or 10 per cent, 
of platinum chloride. 

MeiMs Writing Ink. Platinum chloride, 5 ; lavender 
oil, 15; Indian ink, 15; gum arabic, i; and water, 64 
parts. 

Fireproof Graphite Ink. Graphite, 85 j copal varnish, 
0.08; ferrous sulphate, 7.5; and tincture of galls 30 
parts, with sufficient indigo carmine to give the required 
bluish colour. 

Fireproof Paper. Wood fibre, i part ; asbestos, 2 parts; 
borax, o.i part; and alum, 0.2 part. 



LIST OF ENGLISH PATENTS. 

WRITING AND COPYING INKS. 



Date. 


No. 


Xamc. 


Subject-matter. 


1688 


258 


Holinan. 


Powder for black ink. To be mixed 








with water, beer, &c. 


1764 


809 


Cummings. 


Composition for writing on skins, 








paper, &c. 


1768 


906 


Dring. 


Making ink into a cake or solid. 


1780 


1244 


Watt, 


Copying presses and ink. 


1809 


3214 


Folsch and 


Permanent writing ink. 






Howard. 




1825 


5285 


Giroud. 


Ink from chestnut wood (" damaja- 








vag"). 


1837 


7313 


Stevenson. 


Indelible safety paper (impregnated 








with MnCLj and K 4 Fe(CN) 6 ). 


1837 


7341 


Aldrich. 


Colours rendered applicable to writing. 


1837 


7342 


Stephens and 


Indelible ink. Carbon in solution of 






Nash. 


resinous soap. 


1837 


7474 


Whitfield. 


Indelible ink. Lamp-black in linseed 








oil, &c. 


1839 


8i75 


Normandy. 


Writing inks. 


1840 


8770 


Scott. 


Indelible ink. Gas-black, indigo and 








Prussian blue in gall and logwood ink. 


1843 


9667 


Roberts. 


Composition of ink. 


1844 


10,329 


Mackenzie. 


Writing fluids. 


1846 


">474 


Eeade. 


Indelible ink. Soluble Prussian blue 








in gall ink. 








Also red ink, marking inks, and print- 








ing inks. 


1855 


970 


Depierre. 


Ink from decoction of alder flowers 








and iron salt. 


1855 


1676 


Wood. 


Lake of alum and cochineal dissolved 








in ammonia solution. 


1856 


342 


C. and G. 


Writing and copying ink. Chrome 






Swann. 


logwood ink. 


1857 


1112 


Underwood. 


Copying paper. Writing with logwood 
decoction, and moistening with 








K 2 Cr0 4 solution before copying. 



228 



INKS AND THEIE MANUFACTURE 



Date. 


No. 


Xame. 


Subject-matter. 


1858 


1132 


Henry. 


Copying ink. Addition of glycerin. 


1858 


1996 


Win stone. 


Copying ink. Addition of glycerin. 
(Prov.*) 


1859 


86 1 


Ballande. 


Safety paper. Paper impregnated with 








metallic salt. Ink, a solution acting 








upon the salt. 


1859 


1744 


Scoffern. 


Ink. A solution of animal or veget- 








able fibre in "copperised" am- 








monia. 


1860 


388 


Ballande. 


Safety ink and paper. On lines of pat. 








of 1859. 


1860 


534 


Melville. 


Indelible ink. Plumbago with resin, 








gum, &c., alum, and a suitable colour- 








ing-matter. 


1861 


2972 


Stevens 


Indelible anti-corrosive ink. Aniline 






(Croc.). 


dyes used with carbon. 


1862 


675 


Clark 


Inks from aniline dj es. 






(Annaud). 




1862 


1213 


Koberts. 


Copying ink. Use of glycerin, mol- 








asses, and extract of albemosch seeds. 


1862 


2235 


De la Eue. 


Writing inks from aniline waste, &c. 


1863 


1418 


Friederich. 


Ink from logwood and potassium bi- 








chromate and ferrocyanide. 


1863 


1819 


Goold. 


Alkaline tannate or logwood solution 








treated with metallic iron. (Prov.) 


1864 


2223 


Baildon. 


Safety ink and paper. Colour of paper 








changed by acid in the ink. 


1864 


2506 


Newton. 


Method of oxidising ink. (Prov.') 


1865 


836 


Newton. 


Do. do. do. 


1865 


2267 


Ellis. 


Indelible inks. Colouring-matters pre- 
cipitated by silicic acid and dissolved 








in a soluble silicate solution. 


1867 


106 


Cooley. 


Ink powders. Prepared by extracts of 








dye-stuffs with metallic salts, &c, 


1868 


2163 


Cooke. 


Copying ink. Addition of glycerin. 








(Pror.-) 


1869 


47 


Cooke. 


Copying ink. As in the patent of 








1868. 


1870 


1863 


Pinkney. 


Ink from aniline salts with oxidising 








agent and metallic salt, of which 








nickel is specially claimed. 


1871 


2745 


Pinkney. 


Ink from aniline salt, oxidising agent, 








and uranium or vanadium salt. 


1873 


258 


Gutensohn. 


Ink from tin waste. 


1873 


262 


Halfpenny. 


Incombustible ink and paper. Addi- 








tion of asbestos to paper. Plumbago 








ink. 


1873 


1982 


Carter. 


Oxidising gall ink by air current. 


1873 


3814 


Teysonnieres. 


Prevention of deposits in ink by addi- 








tion of oxalic acid or oxalate. 



WEITING AND COPYING INKS 



229 



Date. 


No. 


Name. 


Subject-matter. 


1873 


3684 


Hyatt. 


Incombustible paper and ink. Addi- 








tion of asbestos. 


1874 


1078 


de Zuccato. 


" Papyrographic " [copying ] ink. Paper 








coated with varnish. Ink, a solution 








of caustic alkali with colouring- 








matter. 


1874 


1839 


Gaffard. 


Indelible ink. Carbon in solution of 








alkali silicate. 


1874 


2009 


Casthelaz. 


Ink obtained by oxidising H 2 S0 4 solu- 








tion of aniline. 


1874 


2939 


Mitscherlich. 


Tannin for ink extracted by heating 








the substance containing it with 








sulphurous acid under pressure. 


1874 


3150 


de Zuccato. 


Improvements in Patent No. 1078 of 








1874. 


1874 


4090 


Petit. 


Copying-ink pencil. Aniline dye with 








plumbago and adhesive material. 








(Prov.) 


1874 


4421 


Knab. 


Black for ink obtained by heating gas- 








tar with lime in a retort. 


1875 


1620 


Grawitz. 


Manufacture of aniline black. 


1875 


4484 


Joly. 


Ink prepared by action of tungstic acid 








on colouring-matters (e.g., of log- 








wood, elderberry, &c.). 


1876 


974 


Byford. 


Dry copying ink powder. 


1876 


4820 


Plateau. 


Portable ink. Absorbent material 








saturated with aniline dye, &c. 


1877 


2389 


Kromer. 


Sympathetic ink. Dry tannin and 








anhydrous ferrous sulphate made 








into paste with benzene and varnish. 


1878 


1586 


Jacobsohn. 


Copying ink powder. Solution of 








aniline dye, sugar, gum, &c., evapor- 








ated to dryness. 


1878 


2636 


Kichmond. 


Indelible ink, containing aniline black, 








and also the substance for forming 








aniline black. 


1878 


4606 


Kwayser and 


Copying ink. Aniline colour in alcohol 






Hasak. 


and water. 


1878 


5122 


Hickisson. 


Ink from vanadium or its salts with 








oxidising agent to form a mordant 








(pref. salt of nickel or copper). 


1879 


526 


Fargue. 


Ink attached to cavity of pen by ad- 








hesive material. 


1879 


2256 


Rosefeld. 


Copying apparatus (gelatin) and aniline 








ink. 


1879 


3391 


Jefferies. 


Aniline inks. 


1879 


3499 


Taylor. 


Formation of aniline black [also as 








marking ink]. (Prov.) 


1879 


4187 


Hardt. 


Aniline and metallic inks for copying 








apparatus. 



230 INKS AND THEIR MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1880 


2606 


Bergel. 


Marking fluid for paper silhouettes 








[KN0 3 solution]. (Prov.) 


1881 


741 


Stoddart. 


Manufacture of ink from spent tan 








liquors. 


1881 


963 


Griinwald. 


Dry copying ink. [Uranium acetate, 








sugar, glycerin with logwood extract 








and alum, or aniline colour]. (Pror.} 


1881 


IOO2 


Priestman anc 


Ink from waste tan liquor and iron 






Longshaw. 


salts. (Proc.) 


1881 


2948 


Schmitt. 


Copying apparatus. Gelatin with 








glycerin and chrome alum. Ink 








which contains uranium salt and 








colour (e.g., indigo), acts chemically 








on substance in the jelly. 


1881 


3410 


Meihe. 


Fireproof ink. Writing or printing 








with ink containing platinum chlo- 








ride on paper containing asbestos. 


1881 


3605 


Gurney. 


Ink from spent tan liquor and iron 








filings. 


1881 


3657 


Sachs. 


Sensitive ink for tracing designs. Ac- 








tion of light on bichromate. 


1882 


7 28 


Reissig. 


Indelible ink. Printing ink incorpor- 








ated with ferrous and ferric salts, 








and thinned with turpentine, &c. 








(JPwr.) 


1882 


3083 


Detmold. 


Aniline or gall inks,"containing alcohol, 








spirit of camphor, &c. Drying in- 








stantly on contact with the paper. 


1883 


859 


Fonseca & 


Indelible ink. Logwood extract, sugar, 






Co. 


aniline black and soot. 


1883 


3600 


Bolton. 


Non-smearing copying ink. Addition 








of ginger and gum arabic to iron 








gall ink. (Pror.) 


1884 


7160 


Friend. 


Papyrographic ink. Iron, tannic acid 








and glycerin. 


1885 


440 


Armour. 


Ink removable by washing. 


1885 


8241 


Frusher. 


Ink from waste logwood, and potas- 








sium bichromate of dyeing vats. 


1885 


9249 


Wass. 


Indelible ink from carbonised sugar 








scum. 


1886 


3!79 


Payne. 


Ink tablet for inking rubber stamps. 


1887 


730 


Himly. 


Sympathetic ink. Magnesium platino- 








cyanide. 


1887 


1 5*079 


Hackney. 


Addition of CaCl 2 to ink to prevent 








drying. Blotting paper containing 








sodium sulphate or borate to decom- 








pose the CaCl 2 , so that the writing 








can dry. 


1887 


17,925 


Groth. 


Indelible ink. Black compound from 








aniline in suitable medium. 



WEITING AND COPYING INKS 



231 



Date. 


No. 


Name. 


Subject-matter. 


1888 


648 


Dimitry. 


Solution of aniline colour with gelatin 








and potassium bichromate. Exposed 








to sun. 


1888 


7H9 


Smith. 


Manifold copying ink (aniline in water, 








HC1 and alcohol), used with slab of 








china clay, starch, glycerin, and 








water. 


1888 


7472 


Quelch. 


Invisible ink. Writing with solution 








of KN0 3 or KC1 on non-glazed sur- 








face, and applying hot wire. 


1889 


2360 


Brasier and 


Writing ink composed of alkaline ex- 






Knowles. 


tract of fibrous plant, Bauhinia 








Vahlii. 


1889 


8 97 I 


Mills. 


Sanitary ink. Addition of an anti- 








septic agent. 


| 1889 


14,388 


Ashton. 


Dry inks. Soluble colours with gum, 








&c., dried on wood, shavings, &c. 


, 1889 


15,565 


Pulford. 


Invisible ink for envelopes. Uranium 








acetate and potassium ferrocyanide 








with white lead applied with litho- 


[ 






graphic varnish. Steam brings about 








reaction. 


1890 


201 1 


Conrad and 


Copying ink. Addition of indigo car- 






Lilley. 


mine and aniline black with glycerin 








and magnesium chloride to an iron 








gall ink. 


1890 


2130 


Tschofen. 


Invisible ink. Writing on smooth sur- 








face with chalk water and dusting 








letters with powder, e.g., graphite. 


1890 


IO,4OI 


Conrad. 


Copying ink. Addition of deliquescent 








salts (e./., ammonium nitrate), and 








glycerin. 


1890 


10,905 


Piffard. 


Copying paper. Paper treated with 








gallic acid iron ink. No press re- 








quired. 


1890 


15,857 


Higgins. 


Ink for stamps. Oleic acid and dye- 








stuff, e.g., methyl violet. 


1890 


15,858 


Higgins. 


Idem. Solution of aniline colour in 








essential oil. 


1890 


16,757 


Just, Weiler, 


Safety ink. Carbon black, vanadium 






and 


compounds, galls, &c. 






Heidepriem. 




1890 


17,373 


Beales. 


Copying ink and prepared paper. No 








damping paper required. 


1891 


1616 


Leech and 


Indelible ink. Turpentine, asphalt, 






Harrobin. 


resin, alum, beeswax and colour. 


1891 


3247 


Coen. 


Copying ink. Glycerin and candied 








sugar in ordinary ink. 


1891 


5437 


Sherwood. 


Copying ink. Soluble aniline dye, 
borax, water, and boiled linseed oil. 



232 



INKS AND THEIR MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1892 


93 


Higgins. 


Stamping ink. Aniline colour with 








fixed oil and carbolic acid. 


1892 


18,721 


Friswell and 
Leeds. 


Copying ink. Lamp-black in solution 
of aniline dye evaporated, and residue 








mixed with lithographic varnish. 


1893 


7263 


Blancan. 


Indelible ink. Aluminium powder with 








protective varnish. 


1893 


16,830 


Hollyer. 


Sanitary ink. Addition of juice of 








lesser celandine. 


1894 


3236 


Nienstaedt 


Dried ink. Granules of non-porous 






and 


substance covered with dried ink. 






Goldmark. 




1894 


5078 


Nienstaedt 


Dried ink. Glass or metal, &c., coated 






and 


with pigment and binding material. 






Goldmark. 




1895 


6938 


Thacker. 


Safety paper. Coated with colour. Ink 








removes the colour of portion written 








on. 


1896 


3459 


Adams. 


Sympathetic ink. Dilute H 2 S0 4 








(i : 17) ; writing made visible by 








heat. 


1896 


17,226 


Temple. 


Non-staining ink. Addition of saline 








compound, e.g., ordinary salt. 


1897 


21,830 


Spencer. 


Dried ink. Aniline dye with sodium 








bicarbonate and acid to produce 








effervescence and diffuse colour in 








water. 


1897 


21,991 


Holler. 


Invisible and indelible ink. Alum 








and white garlic juice visible on 








heating. 


1898 


5294 


Izambard. 


Use of Bontgen rays in writing. 


1898 


24,644 


Lichtentag. 


Indelible ink. Carbon in soap and 








water or other medium. 


1899 


6727 


Kretschmaun. 


Sympathetic ink. Paper treated with 








solution of cobalt chloride. Ink a 








solution of rock salt. 


1899 


8976 


Bachem. 


Sympathetic ink. Two substances, 








e.<jr., cobalt chloride and magnesium 








platino-cyanide, one becoming visible 








and other disappearing on heating. 


1899 


14,957 


Power. 


Eapidly-drying ink. Tincture harn- 








amelis, tincture of iron, and gum 








arabic in spirits of wine. 








Ked ink from rose petals. 


1900 


1290 


Izambard. 


Copying by means of Rontgen rays. 


1900 


7367 


Kretschmann. 


Sympathetic ink. Paper treated with 








non-hygroscopic cobalt salt. Writing 








with solution of salt and substance 








(e.g., vinegar) to produce hygroscopic 
salt. 



MARKING INKS 



233 



Date. 


Xo. 


Name. 


Subject-matter. 


1900 


3807 


Brown . 


Copying paper. Paper treated on one 
side with hardened gelatin, and on 
the other with deliquescent substance 
(e.g., CaCl 2 ), and solution of substance 
not affected by writing ink. No 
damping required. 



MARKING INKS. 



1848 


11,474 


Reade. 


Ammoniacal solution of silver tartrate. 








Addition of gold salts. 


1856 


738 


Bufton. 


Platinum salt (Pt 2 Cl 6 ), added to the 








silver. (P)-or.) 


1858 


2316 


Dunn. 


Harking ink pencils. Silver salts with 








black lead or other provisional 








colouring -matter. 


1864 


1828 


Holler. 


Red ink-madder with cochineal, ma- 








genta or carmine. Alum as mordant. 








(Prov.) 


1864 


2511 


Holler. 


Hadder extract with alkali salt in alco- 








hol + gum and vermilion. Alum 








used previously as mordant. 


1877 


379 


Schroll. 


Harking ink pencil. Composition of 








clay, silver nitrate, or other soluble 








silver salt and plumbago. 


1878 


5122 


Hickisson. 


Vanadium salts, with oxidising salt as 








mordant. For solid pencil, gum, dex- 








trin, clay, &c., added. 


1879 


3499 


Taylor. 


Formation of aniline black within the 








fabric. 


1880 


1771 


Johnson. 


Impregnating fibres with mixture con- 








taining ortho-nitro-phenyl-propiolic 








acid, reducing agent and alkali, and 








developing with heat. 


1880 


1838 


Sachs. 


Formation of dye-stuffs from poly- 








sulphides of heavy metals. 


iSSi 


466 


Johnson. 


Use of sulphides or sulpho-compounds 








of alkali metals as reducing agents in 








previous patent. 


1882 


5946 


Langbeck. 


Coloured marking inks. Salicylic acid, 








turpentine oil, spirits of wine, gly- 








cerin, and colouring-matter (ver- 








milion, &c.). 


1883 


751 


Hickisson 


Colour mixed with solution of caout- 






and Lang- 


chouc in carbon bisulphide. 






beck. 





234 INKS AND THEIR MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1883 


75 2 


Hickisson 


Colour mixed with base of arsenic 






and Lang- 


pentoxide, turpentine, and glycerin. 






beck. 


Pencils from same mixture. 


1884 


9149 


Hickisson. 


Pencil with marking point (AgN0 3 








with KN0 3 ) at one end and mordant 








(pyrogallol, wax and borax) at the 








other. 


1884 


I5.96I 


Hickisson. 


Mordant for pencil. Moistened and 








applied to linen. 


1885 


3980 


Simpson. 


Mordants rendering ordinary writing 








insoluble in water. 


1888 


647 


Doniitry. 


Soluble colour with gelatin and potas- 








sium bichromate, writing exposed to 








sunlight. 


1893 


5316 


Hickisson. 


Aniline dyes soluble in oil dissolved in 








e.g., castor oil, and solutions 








thinned with turpentine. For pencils, 








mixed with suitable base. 



PRINTING INKS. 



1772 


1012 


Kowley. 


Ink for printing playing cards in 








colours. 


1821 


4601 


Martin and 


Soot of burnt coal-tar as pigment. 






Grafton. 




1831 


6l82 


Smith and 


Delible ink for copying books. 






Dolier. 




1835 


6906 


Bird. 


Printing ink. Use of a mineral earth 








as pigment. 


1853 


483 


Goodell. 


Use of residue from purification of rosin 








oil. 


1853 


1900 


Gwynne. 


Powdered coal as pigment. 


1853 


I92O 


Newton. 


Use of residue from distillation of 








rosin oil. 


1853 


2243 


Maumene. 


Carbonised lignite as pigment. 


1854 


1575 


Archer. 


Paper carbonised with sulphuric acid 








as pigment. 


1854 


2490 


De la Rue. 


Addition of glycerin. 


1855 


3 2 


Livesay. 


Ordinary typographic ink mixed with 








varnish, rosin, and Venice turpen- 








tine. 


1855 


320 


Kuhlmann. 


Addition of silicates to letterpress ink. 


1855 


I9l8 


De la Kue. 


Addition of manganese borate. 


1856 


400 


Grant. 


Addition of odoriferous essential oils. 


1856 


516 


Brooman. 


Pigment from bituminous shale and 








schists. 



PRINTING INKS 



235 



Date. 


No. 


Xame. 


Subject-matter. 


1856 


2206 


Underwood 


Copying printing ink. (Gall and fer- 






and Burt. 


rous sulphate. ) 


1857 


III2 


Underwood. 


Copying printing ink. (Logwood ex- 








tract.) 


1857 


I5l8 


Matthews. 


Green ink. Chromium oxide and var- 








nish. 


1857 


1744 


Seropyan. 


Ink for cheques. 


1858 


1187 


Stuart, 


Residue from distillation of bitu- 








minous substances as pigment. 


1859 


I 3 


Viette. 


Lithographic ink containing : gutta- 








percha. 


1859 


348 


Moss. 


Tnk for cheques. 


1859 


1282 


Hadfield. 


Apparatus for varnish manufacture. 


1859 


2081 


Collins. 


Transfer ink. 


1859 


2399 


Palmer. 


Aniline by-product as pigment. 


1860 


3 88 


Ballande. 


Safety printing ink. 


1860 


*445 


Thierry. 


Pigment prepared from carbonised 








schist. 


1860 


2640 


Neal. 


Grinding mills. 


1862 


767 


Brooman. 


Inks for printing on glass. 


1862 


2654 


Prince. 


Use of petroleum products in litho- 








graphic varnish. 


1862 


374 


Croc. 


Telegraph ink. Aniline in dilute alco- 








hol, thickened with gluten. 


1863 


i5 6 4 


McLean. 


Pigment from shale. (Pr,ov.) 


1863 


3204 


Hughes. 


Ink for cheques. Compound of stannic 








acid and chromium oxide. 


1864 


2854 


Rowley. 


Use of pitchy substance from distilla- 








tion of cotton oil. 


1865 


3325 


Newton. 


Oil substitute prepared from glue or 








gelatin. 


1866 


367 


Holmes. 


Animal pitch (bone oil pitch) as lamp- 








black substitute. (P/w.) 


1866 


X 737 


Holmes. 


Idem. 


1868 


2578 


P. and W. 


Pigments. Oxides of iron heated with 






Hodge. 


carbonised peat. 


1869 
1869 


439 

2890 


Binko. 
Kirchner 


Indigo printing ink. 
Delible printing ink. Ferric hydroxide 






and Ebner. 


with tannin in a varnish. 


1869 


2946 


May. 


Non-oleaginous inks. Glycerin, gums, 








and pigment. 


1869 


2993 


Kloen. 


Water-colour inks. Pigments with 








glycerin, gums, sugar or other sub- 








stances soluble in water. 


1869 


3543 


Edwards. 


Photo-mechanical ink. Extra greasy 
ink. 


1870 


967 


Jackson. 


Grinding mills. 


1870 


1419 


Lawrence. 


Ink containing glycerin, gum, sugar, 








and pigment. 



236 INKS AND THEIR MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1870 


1863 


Pinkney. 


Use of aniline salts with nickel salts 








and an oxidising agent. 


1870 


2762 


Lake 


Use of petroleum products. 






(Toppan). 




1871 


689 


Lake. 


Copying ink. Use of pigment soluble 








in water and of soluble gums. 


1871 


2745 


Pinkney. 


Use of aniline salt with salts of vana- 








dium and nickel. 


1871 


3365 


McCready. 


Apparatus for blending colours. 


1873 


2133 


Little. 


Telegraphic apparatus. Ink of aniline 








blue in glycerin. 


1873 


3129 


Mackay, 


Use of oil recovered from waste 








fabrics. 


1873 


3176 


Newton. 


Pigment for printing fabrics. 


1873 


3598 


Kingdon. 


Grinding mills. 


1873 


3684 


Hyatt. 


Fireproof ink. Addition of asbestos 








powder. 


1873 


3809 


Smith and 


Heating printing ink to uniform tem- 






Fountain. 


perature before use. 


1873 


4196 


Thomas. 


Use of heavy oils and pitches from 








tar. 


1874 


208 


Clark. 


Apparatus for manufacture of lamp- 








black. 


1874 


1078 


de Zuccato. 


Papyrographic ink. Caustic alkali 








solution and vandyke brown. 


1874 


1839 


Tongue. 


Carbon in a silicate solution as indelible 








ink. 


1874 


1995 


Clark. 


Stamping ink. Solution of colour in 








alcohol and glycerin. 


1874 


4421 


Knab. 


Manufacture of pigment from gas tar, 








&c. 


1875 


605 


Whitburn. 


Ink for printing on wood. 


1875 


1620 


Clark. 


Production of aniline black for print- 








ing- 


1875 


1941 


Holyoake. 


Transfer ink. (P;v>r.) 


1875 


3762 


Edison. 


Ink for autographic printing. Printers' 








ink thinned with castor oil. 


1876 


1662 


Heuer. 


Printing on glass. 


1876 


2268 


Brooks. 


Coloured printing inks. Special var- 








nish. 


1876 


2621 


Zingler. 


Metallic printing inks. Solution of 








albumen as vehicle. 


1876 


3270 


Tongue. 


Pigments from anthracite and other 








coal. (P/w.) 


1876 


4470 


Pinkney. 


Ink for cheques. Use of ferrocyanides 








with aniline or vegetable colours. 


1877 


169 


Tongue. 


Pigments from anthracite, &c. (Pror.) 


1877 


895 


Pumphrey. 


Autographic ink. Aniline colours in 








acetic acid and glycerin. 


1877 


950 


Williams. 


Boiling oil. Use of steam. 



PRINTING INKS 



237 



Date. 


No. 


Name. 


Subject-matter. 


1877 


3402 


Howard. 


Pigment from peat charcoal. 


1877 


3407 


L'Heureux 


Engraving ink containing sugar, gum 






and Ligny. 


arable, and silicates. 


1878 


2706 


Listen. 


Ink for printing on earthenware. Pig- 








ment with glycerin or molasses. 


1878 


5098 


Winterhoff. 


Ink for china, wood, iron, &c. Pigment 








with varnish of oil, resins, Venice 








turpentine, wax, suet and flux. 


1879 


141 


Haddan. 


Metallic powder incorporated with 








solution of silicate. 


1879 


402 


Cunnack 


Kaolin clay as a base for the pigment. 






and Argall. 




1879 


2518 


.Gray. 


Preparation of varnish by treating oil 








with hot air. 


1879 


339i 


Jefferies. 


Transfer ink. Treacle and glue. 


I8 79 


4204 


Nesbit. 


Ink for cheques. Aniline printing ink. 


1879 


4524 


Gestener. 


Water colour transfer ink. Mixture 








of a water colour pigment in aniline 








with glycerin, varnish, syrup and 








mineral pigment. (Pwr.) 


1879 


4645 


Kesseler. 


Ink for zincography. Pitch, tar oil, 








fatty acid, aniline violet and residue 








from distillation of rosin oil. 


1879 


4788 


Imray. 


Transfer printing inks. 


1879 


4997 


Haddan. 


Ink for cheques. Bichromate, ferrous 








sulphate, ferrocyanides, logwood, 








oxalic acid and glycerin. (Prov.) 


1879 


5 2 3 2 


Wirth. 


Coal tar as pigment. (Prov.~) 


1880 


827 


Pfleiderer. 


Ink for glass. Pigments with copaiba 








balsam, Venice turpentine, rosin oil 








and driers. 


1880 


1028 


Klein. 


Ink for printing oil cloth. 


1880 


1615 


Alexander. 


Pigment from bitumens and hydro- 








carbons. (.P/w.) 


1880 


1838 


Sachs. 


Use of dyeing substance in printing 








ink. 


1880 


1971 


Savigny and 


Use of a special vegetable colouring- 






Collineau. 


matter. 


1880 


2216 


Kessseler. 


Ink from pitch, fatty acid, aniline 








violet, and tar oil. 


1880 


34i8 


lingerer. 


Colouring composition for impression 








rollers. (P>w.) 


1880 


459 1 


Bertram. 


Flexible ink. Aniline, acetic acid, glu- 








cose, glue, glycerin and water. 


1880 


4693 


Bastand. 


Use of oil from cotton waste. 


1880 


4846 


Witt. 


Ink for calico printing. 


1880 


4874 


Boult, 


Ink for celluloid. Aniline colours in 








carbolic acid. 


1881 


375 


Dupr6 and 


Ink for cheques. 






Hehner. 





238 



INKS AND THEIE MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1881 


436 


Poirson. 


Transfer ink for leather, &c. Con- 








taining salts melting in their water 








of crystallisation, e.g., alum or sodium 








sulphate. 


1881 


814 


Marie and 


Use of nitric esters of sugars. (Pw.) 






Bouneville. 




1881 


903 


Gard and 


Use of tannin black from leather waste 






Cobley. 


as lamp-black substitute. 


1881 


1002 


Longshaw 


Tannin black from spent tan liquors. 






and 


(Pror.) 






Priestman. 




1881 


1203 


Brackebusch. 


Printer's varnish without linseed oil. 








Colophony and paraffin oil. (Prov.} 


1881 


2IO3 


Bastand. 


Use of oil extracted from engine cotton 








waste. 


1881 


2274 


W. G. and 


Polychromatic printing ink containing 






K. R. White. 


aniline dye-stuffs, &c. 


1881 


2868 


Jensen. 


Ink from pitch, anthracene oil, tar oil, 








aniline colour and lubricating soap. 








( Void.) 


1881 


3410 


Meihe. 


Fireproof printing ink. Use of asbestos 








powder. 


1881 


3605 


Gurney. 


Tannin black from waste tan liquors. 


1881 


3 6 57 


Sachs. 


Ink for impressions of patterns. Chro- 








mium compound, &c. 


1881 


3762 


Clark. 


Autographic transfer ink. Contains 








proteids, bichromates, ferrocyanides 








and alums. 


1882 


728 


Keissig. 


Indelible printing ink. Linseed oil 








varnish, lamp-black, and ferric chlo- 








ride. (Prov. ) 


1882 


3086 


Wirth. 


Manganese peroxide as pigment. 


1882 


3248 


Gibson. 


Metallic inks. Metallic powder mixed 








with naphtha and solution of rubber 








in carbon bisulphide. 


1882 


4106 


Glaus. 


Iron sulphide incorporated with rosin, 








fum, or fused sulphur. 


1883 


949 


Nesbit. 


for cheques. Use of decoction of 








alkanet root. 


1883 


3638 


Lake. 


Ink for india-rubber goods. Caout- 








chouc, naphtha, red lead, and sul- 







phur. 


1854 


2268 


Baseley. 


Grinding mills. 


1885 


9249 


Wass. 


Pigment from sugar scum. 


1885 


9413 


Macrone. 


Varnish from seed oil, rosin, paraffin 








wax, beeswax, and copal varnish. 


1886 


606 


Brousset. 


Varnish for fixing transfers. Mineral 








pitch, heavy benzine, and copaiba 








essence. 



PRINTING INKS 



Date. 


Xo. 


Name. 


Subject-matter. 


1886 


1601 


Gutheil. 


Lithographic ink of intense colour. 








Venetian soap, wax, mastic, shellac, 








Venice turpentine, lamp-black or 








soot rubbed with water for use. 


1887 


1076 


Schlum- 


Addition of vegetable colouring-matter 






berger. 


(alizarine) altering colour on addition 








of alkali. (Opposed and not granted.') 


1887 


17,925 


Groth. 


Antiseptic ink. Aniline black in 








aniline, carbolic acid, &c. 


1888 


3321 


Bensinger. 


Ink for celluloid. Aniline dye-stuff in 








carbolic or acetic acids. 


1888 


13,968 


Neilson, 


Antiseptic ink. Use of permanganate 






Harrap and 


or pigments used in sanitary wall- 






Brown. 


paper. 


1888 


15,457 


Jones. 


Invisible printing ink. Cobalt salt in 








dilute alcohol. Inking rollers to be 








covered with absorbent material, e.g., 








flannel. 


1889 


6287 


Weight. 


Sanitary ink. Part of paper rendered 








transparent with " medicating oil." 


1889 


8971 


Mills. 


Sanitary ink. Addition of antiseptic . 


1889 


I5, 8 39 


Browne. 


Use of semi-fluid bitumen (maltha) 








with or without black pigment . 


1889 


20,830 


Huelser. 


Use of fine coal dust as pigment. 


1890 


11,168 


Holt. 


Ink from residue from distillation of 








petroleum with resin, gum, and pig- 








ment. 


1890 


1 5,743 


Davison. 


Imitation metallic printing inks. Nitro- 








benzene aniline product, picric acid, 








varnish, spirit, soap, rosin, &c. 


1890 


16,689 


Lake. 


Non-clogging ink. Vaseline, fatty oil, 








and pigment. 


1890 


16,757 


Just, Weiler, 


Ink for cheques, &c. Black from sugar, 






and Heide- 


or carbon black, caustic potash, oxalic 






priem. 


acid, Indian ink, vanadium com- 








pound, galls, gum arabic, aniline 








colour, and water. 


1891 


873 


Hudson and 


Antiseptic ink. Permanganate or 






Hills. 


eucalyptus, &c., with glutinous com- 








pound. 


1891 


12,104 


Brandt. 


Zincographic ink. Antimony black, 








bone black, resins, strong varnish, 








Berlin blue and ordinary printing 








ink. 


1891 
1891 


12,200 
17,635 


Bertling. 
Dreyfus. 


Lithographic transfer ink. 
Kesinates of coal tar dye-stuffs used as 








pigments . 


1892 


I2,28o 


Chamberlain. 


Ink for cartridge case. Varnish, pig- 








ment, and drying oil. 



240 



INKS AND THEIR MANUFACTURE 



Date. 


No. 


Name. 


Subject-matter. 


1893 


7263 


Blancan. 


Metallic ink. Aluminium powder with 








protective varnish. 


1893 


12,863 


Bibby. 


Use of cotton seed "foots" with other 








usual ingredients. 


1894 


6268 


Degroote and 


Colour printing ink. Pigment, boiled 






Aulnois. 


linseed oil, siccative and caoutchouc. 


1894 


13,676 


Cardeaux. 


Printing from raised type on tin foil. 








Addition of vaseline to ink. 


1894 


20,423 


Barnwell. 


Printing several colours in one im- 








pression. Inks in strips on rollers 








prevented from mixing by addition 








of castor oil, turpentine, tar oil, 








copaiba balsam, sulphuric ether, am- 








monia, and ipecacuanha. 


1895 


955 


Priestley and 


Metallic inks. Bronze powder, &c., 






Swann. 


with varnish and lard or fat. 


1895 


6938 


Thacker. 


Inks for wood, canvas, paper, &c. 








Surface covered with coloured layer 








which can be removed by suitable 








chemicals. (Cheque ink.) 


1895 


17,868 


Hallet. 


Printing ink for imitation type- 








writing. Aniline dye-stuff used. 


1896 


8376 


Taylor and 


Printing in several colours in one im- 






Cooke. 


pression. Inks prevented from 








mixing by addition of copaiba bal- 








sam, glycerin, sandal wood oil, petro- 








leum, turpentine, tincture of myrrh, 








chloroform, and ammonia. 


1896 


12,198 


Torrance. 


Grinding and mixing mill. Differen- 








tial gearing for rotating rollers at 








different speeds. 


1896 


16,274 


Sharp. 


Metallic ink suitable for stencil 








machines. Metallic powder with 








gum arabic, linseed oil, rosin oil, dex- 








trin, red lead, litharge and turpentine. 


1896 


18,131 


Michel- 


Coloured ink. Albumen preparations 






Dansac and 


with specified coloured pigments. 






Chassagne. 




1896 


26,992 


Webb. 


Safety ink for copper and steel plate 








printing. Aniline colour in base 








of flour and magnesium oxide with 








sodium carbonate and soap. 


1896 


30,121 


Boult, 


Metallic ink (" direct-ivr "). Varnish 








and oils, rosin, &c., with bronze powder. 


1897 


7399 


Gentele. 


Cellulose or wood powder as sub- 








stratum for colour. 


1897 


9121 


Taylor. 


Printing in several colours simultane- 








ously. Addition of powdered man- 








ganese and alcohol to substances 








enumerated in Pat. 8376 of 1896. 



PRINTING INKS 



241 



Date. 


No. 


Name. 


Subject-matter. 


1897 


i8,533 Ogilyy. 


Mixed pigments and varnish incorpo- 








rated by use of superheated steaui 








or steam under pressure, and volatile 








products condensed. 


1897 


?9-753 


Webb, 


Fugitive safety ink. Base of dextrin 








and treacle with glycerin, aniline 








dye-stuff and antiseptic agent. 


1897 


23.080 


Hadley and 


Ink for etched designs on glass, &c. 






; Sephton. 


Contains wax, Canada balsam, soap, 








and lamp black. 


1897 


24,504 


Stoop. 


Substitute for linseed oil. Use of 








drying mineral oils, e.g., grisee oil. 


1897 


29,7-28 


Banner. 


Substitute for linseed oil. Colophony 








in suitable solvent wholly or par- 








tially saponified with caustic soda 








or sodium silicate ; or use of lime- 




i 




rosin. 


1897 


30,104 


Burger. 


Inks used in production of colour 








prints. 


1898 


5294 


Izambard. 


Radiographic or X-ray proof ink. 








Metallic or calcareous powder with 








boiled oil and alkali bromide. 


1898 


n^S 1 


Gotliffe. 


Printing waterproof fabrics. Metallic 








powder (nickel) with egg albumen 








or other thickening agent. 


1898 


20,356 


Pitt. 


Use of gelatinous compound from 








kelp. 


1898 


23,071 


Stoop. 


Use of natural drying mineral oil 








(grisee oil) in varnish. 


I8 99 


'7,557 


Printing 


Use of inks of different consistency in 






Arts Co. and 


colour printing. 






Orloff. 




1900 


W45 


White. 


Polychromatic printing. Special sheets 








of composition containing the 








colours. 


1900 


14,886 


Ogilvy. 


Admixture of ink effected by heating 








and mechanical agitation. No mill 








used. 


1900 


17,126 


Hofer. 


Ink for printing transparencies on 








celluloid. Pigments and mixture of 








ether, camphor, paraffin oil and man- 








ganese. 


1900 


17,783 


Stevenson. 


Printing designs changing colour on 








exposure. Use of combination of 








permanent and non-permanent 








colours. 


1900 


23,231 


British Oil 


Use of residuum from purification of 






Mills Co. 


cotton-seed oil. 






and Wass. 





242 INKS AND THEIR MANUFACTURE 



Date. 


Xo. 


Xaine. 


Subject-matter. 


1901 


1366 


Hoz. 


Use of dyeing pigments and develop- 








ment and fixing of printing on the 








fabric. 


1901 


5168 


Imray. 


Use of iodophenolthiosulphonates as 








pigments. 


1901 


6061 


Wass. 


Use of solution of rosin in mineral 








oil as varnish. 


1901 


8645 


Tellkamp. 


Autographic ink. 


1901 


12,826 


Wechsler. 


Lithographic printing. Ink for con- 








tinuous working. Pigment, varnish, 








glycerin, alkali salt, tartar, and 








turpentine. 


1901 


23,892 


Lilienfeld. 


Fixing varnish for pigments for textile 








fabrics. 


1902 


8371 


Schmiedel. 


Production of dark shade on coloured 








ground. Use of a solution of a resin 








with or without glycerin. 



INDEX. 



ACIDITY of inks . . . 123 

Acorn galls ...... 45 

Alder bark 65 

Aleppo galls .... 38 

Algarobilla 66 

tannin ..... 62 
Alizarine .... 175, 177 

in marking inks . 205 

in printing inks . 176 

orange . . . . 174 

red 176 

yellow . . . . 174 
" Alizarine " inks . 13, 94 
Alumina for printing 

inks 165 

Aluminium powder in 

inks .... . . 212 

Anacardic acid . . . 196 

Anacardium occidentale 195 

orientale . . . ; 193 

Andre's apparatus . . 145 

Aniline black inks . . 1 1 1 

copying inks . . 189 
dye-stuffs, fugitive- 
ness of . 116, 172 

in gall inks . 97 

ink powders . . . 220 

marking inks . . 203 

printing inks . . 172 
writing inks . . 13,115 

Antwerp blue . . . . 115 

Aphides of galls ... 45 

Apples of Sodom ... 49 



" Art shades " in print- 
ing inks 177 

Aspergillus niger ... 67 
Atramentum . . . . 7, 35 
Aureolin 115,173 

BAILDON'S safety paper 213 

Ballande's safety paper 213 

Bank-notes, ink for . . 183 

Baryta white . . . . 1 74 

Bassorah galls .... 48 
Baudrimont's soluble 

glass ink 209 

Beau Chesne's book . . 12 
Bichromate logwood 

inks 107 

marking inks . . 202 

Bistre 136 

Black for printing inks . 150 

mixing 160 

printing inks . . 151 

writing inks . . 87, 

99, 109, in 

Bleaching writing . . 127 

Block books . . . . 134 

Blue aniline inks . .117, 220 

galls 38 

paper 213 

pigments . . 115, 176 

printing inks . . 1 76 

sympathetic inks . 215 

writing inks . . . 114 
Blue-black inks . 13, 94, 97 



244 



INDEX 



Blue-green inks ... 97 

Boiled oils 141 

Boiling apparatus . . 145 

processes . . . . 142 

Books, block . . . . 134 

Dutch 135 

early printed . . 134 
German . . . . 135 
Italian . . . .135 
Brazilwood . . .113,114 
Breton's method (print- 
ing ink) . . . .--;; 138 
British galls .... 46 
Brown madder . . . 176 
pigments for print- 
ing ink . . . . 177 

Burnt oil 142, 145 

Sienna - . . . 115, 175 

CADMIUM orange . . . 175 
yellow . . . . . 115 

Cancelling ink . . . . 223 

Carbon blacks . . . . 153 

examination of 157 

inks . . . 5, 34, 207 

transition to . 9 

Cardol ...... 196 

Carmine. . . . 115, 176 

Cashew nut . . . .195 

Catechu ...... 52 

tannin . . . . . 51 

Cheque inks . . . . 183 

Chestnut bark 52 

extract .... 52 
ink from . . . 54, 119 

shells 54 

tannins . . . 51, 53 

Chinese galls .... 40 

aphis of ... 45 

Chinese ink . . . 5, 23 

composition of 33 

manufacture of 28, 



qualities of 



30 

3 1 



Chinese ink, tests of . 32 

Chinese printing . . . 133 

Chrome logwood inks . 105 

yellow 115, 

174, 175 

Chromium oxide . . . 115 
Clerk-Maxwell's curves 180 
Coal-tar colours for inks 1 1 5 
Coarse-grain screens . . 170 
Cobalt in printing inks . 177 
salts in sympathetic 

inks . . ... 215 
Cochineal in inks . 1 1 3, 1 76 
Colour, diagrams of . . 1 70 
photographic falsi- 
fication of . . . 178 
theory of . . . . 170 
curves . .. .. . 180 
screens . . . . 180 
Coloured light . . . . 1 8 1 
pigments . ... . 181 
printing inks . 164,167 
screens . . . . 179 
writing inks . . . 112 
Colours, fugitive . . . 173 
permanency of . 115,172 
Consular diptychs . . 4 
Copper logwood ink . . 105 
marking inks . . 203 
Copying apparatus . . 191 
ink pencils , . . 190 

inks 1 86 

papers . . . . 190 
Coriaria myrtifolia . . 56 
thymifolia . . . 192 
Corrosiveness of inks . 96, 123 
Crimson lake . . .115,173 
Cuthbert, Gospels of St. . 8 

Cuttle-fish 15 

fossil 17 

ink from .... 1 8 

ink-sacs of ... 15 

species of . . . . 1 8 

Cynipidae , , . . 36, 47 



INDEX 



245 



DAMAJAVAG' . . . . 54 


Gall inks ... . . 


87 


Dandelion juice . . . 198 


wasps . . . -36. 


47 


Dieterich's school ink . 108 


Gallic acid 


68 


Digallic anhydride . 66, 67 


inks . ...":. 96, 


103 


Divi-divd . . ... 57 


reactions of 


69 


ink from .... 59 


Gallotannic acid . . . 


66 


tannin of . . . 58, 62 


composition of 


67 


Domestic ink-making . 10 


determination 




Double-tone inks . . . 178 


of .... 


80 


Dried inks 221 


fermentation of 


43, 


Driers 142 




67 


Drop black . . .-.'. . 153 


properties of . 


/ 

68 


Dryin ' oils 141 


reactions of . 


69 


Durham book .... 8 


Galls 


:? 

^6 


Dutch books . . . . 135 


acorn 


3 

4.C 


printing ink . . . 137 


Aleppo .... 


T- j 

3 




Bassorah . . . . 


48 


EGYPTIAN papyri ... i 


blue 


?8 






o^ 


Electric process of mak- 


Chinese 


40 


ing varnish . . . . 149 


French .... 


48 


Elizabethan inks ... 1 1 




38 


Ellagic acid . . . . 5 1 , 68 


Japanese .... 


o 
43 


Ellagitannic acid . 58, 60, 62 


Knoppern 


46 


Emerald green . .115,177 


Levant . . . - . 


38 


English books . . . . 133 


manufacture of ink 




Eosine inks . . .116,117 


from ...... 


87 


Examination of hand- 


Mecca . . . . . 


48 


writing . . 124 


oak-apple . .. 


46 


inks . . . . 119 


origin of . ...'.* 


36 


marking inks . 205 


proportions for ink 


87 




Piedmontese . . 


45 


FERTEL'S printing ink . 137 


pistachio .... 


48 


Fireproof inks . . . . 225 


red 


48 


papers 226 


Smyrna .... 


7Q 






3:7 


Flake-white . . . . 174 


tamarix .... 


4 8 


Flea-seed galls ... 36 


tannin in . 


66 


Fluidity of inks . . . _i 20 


Turkey .... 


38 


Forged handwriting . . 126 


white 


30 


detection of , 127,130 


Gamboge . . . .114, 


O *7 

US 


Frankfort black . .153,158 


Gas-blacks 


153 


French galls .... 48 


composition of . 


157 


Fugitive colours . . . 173 


manufacture of . 


154 




German black . 


28 



GALL aphides 



44, 45 



books 135 



246 



INDEX 



German ink regula- 

lations . . . . 14, 119 

Glass, inks for writing on 223 

Glycerin in inks . . . 187 

Gold inks . . . . . 113 

marking inks . . 201 

Graphite ink .... 226 

Green galls 38 

pigments . . . . 115 

printing inks . . 117 

writing inks, 112, 114,117 

Green-black ink ... 97 

Griessmayer's reaction . 70 

Grinding machines . . 162 

Grisel oil 150 

H^MATEIN 101 

inks 108 

Haematoxylin . . . 74, 100 
ink powders . . . 220 
Half -tone dot . . . 182 
process block . . 169 
Handwriting, differen- 
tiation of . . 127 
examination of . . 1 24 
forged . . . . 126 
methods of bleach- 
ing 127 

Hemlock tannin ... 52 

Herberger's safety ink . 209 

Herculaneum fragments 4 

Hop-stalk juice . . . 198 

Hydrocarbon blacks . 153 
Hydrogen peroxide as 

reagent for tannin . 7 1 

Hydrofluoric inks . . 223 

INDIAN ink 5, 23 

composition of 33 

examination of 32 

manufacture of 28, 

30 
practical tests 

Of . 32 



Indian ink, qualities of 3 1 
marking nut . . . 193 
red . . . . 115, 176 

yellow 115 

Indigo . . . . .115, 204 

detection of . . . 121 

in " Alizarine " inks 94 

in coloured inks . 114 

in printing inks . . 177 

permanency of 94, 173 

Indigotin marking inks . 204 

Indulin inks . . . . 1 1 1 

Ink deposits .... 89 

plant 192 

powders .... 219 

tablets 219 

Ink-forming substances 72 

Inks, action on pens . . 123 

" Alizarine " . 13, 94 

aniline . . 13, 111,115 

carbon 5 , 1 5 

coloured printing, 164, 167 
writing . . . 112 
composition of . . 121 
copying . . . . 186 
examination of . . 119 
for special purposes 219 
influence of light 

and air on ... 74 
logwood .... 99 
marking . . . . 192 
printing . . . . 132 
properties of good . 119 
vanadium . . . 109 
vegetable . . . . 192 
Iron-blueing tannins, 50,52,66 
Iron deposits from ink, 78, 89 
greening tannins, 50, 5 2, 63 
tannates . . 75, 76, 79 
Iron-gall inks . . . . 7, 9 
composi- 
tion of . 121 
examina- 
tion of . 119 



INDEX 



247 



Iron-gall inks, manufac- 
ture of . 87 
old formu- 
lae for . 93 
oxide (intermediate 
blue) .... 75 
(pigment) . . 176 

Isatin inks 94 

Isochromatic plates . . 179 

Isohaematein .... 102 

Italian books . . . . 135 

Ivory surfaces, inks for . 225 

JAPAN inks .... 98, 121 

Japanese galls .... 43 

aphis of ... 45 

ink from . . 92 

tannin of . 44 

Jeserich's photographic 

method 131 

Jet black 153 

KETTLES for boiling oil . 145, 

146 

Key blocks . . . . .183 

King's yellow . . . . 174 

'Kino 65 

tannin . 51 

Knoppern . . . ... 45 

ink from . . . 46, 65 

LAMP-BLACK .... 24 

calcining . . . . 156 
composition of . 24,157 

examination of . . 157 

furnaces . . . . 152 
manufacture of . 25,151 

purification of . . 155 

substitutes f or . . 153 

varieties of ... 28 

Larch 65 

Leather, inks for . . . 225 

Lehmann's mills . . . 162 

Lindisfarne Gospels . . 8 



Linolenic acid . . . . 141 

Linolic acid . . . . 141 

Linseed oil 141 

substitutes . . 150 

Lithographic ink . . . 1 64 

varnish .... 141 

composition of 145 

varieties of . . 144 

Logwood 99 

detection of . . . 128 

extract . . . . 100 

in gall inks . . . 102 

in patent inks . . 108 

ink powders . . . 219 

inks 103 

MADDER . . . . . 175 

carmine . . . . 176 

lake 182 

Manganese marking ink 203 
Manuscripts, Anglo- 
Saxon .... 34 
British >. . . . ' 8 
deciphering ... 124 
ink of old . . 4, 8, 10 
Spanish .... 8 
Marking ink pencils . . 205 

inks 192 

alizarine . . 205 
aniline . . . 203 
chemical . . 199 
examination of 205 
patent . . . 233 
vegetable . . 192 
Marking nut . . . . 193 
Melanin from sepia . 19,21 
Metagallic acid . . 50, 53 
Metals, ink for . . . 224 
Milton's Bible . ... 9 
Mixing machines . . . 160 
Molybdic marking ink . 202 
Moxon's " Mechanick Ex- 
ercises " 136 

Murex 112 



248 



INDEX 



Myrobalans 

ink from . 
tannin of . 

NAPLES yellow 
Newspaper ink 
Niger-seed oil . 
Nigrosine 
inks 

Non-drying oils 
Nut galls . . 
Nut oil . 



59 
60 
60 



173 

160 

. 141 

in 

. 128 
. 141 
38, 86 
. 141 



OAK-APPLE galls ... 46 
ink from . 47, 92 
Oak-bark, amount of 

tannin in ... 64 

ink from .... 65 

tannins . . . 51,63 

reactions of .64 

Oak-red 63 

Ochre . . ... . . . 178 

Oils, boiled ..... 145 

process of boiling . 142 

used for varnish . 141 

Olive green 115 

Orange pigments . . .177 

Overlays . . . . . 170 

Oxidised gall extract . 96 

linseed oil ... 149 

tannin solution . . 96 

Oxygen treatment of 

oils . . ...... . . 148 

Ozone treatment of 

oils . . ...... 149 

PAINTERS' pigments . 168 

Palimpsests . . . . 125 

deciphering . . . 126 

Paper, composition of . 9 

Papyri . . .... 5 

Egyptian .... i 

Greek . 2 



Papyri, Hercuianeum . 4 

Paris green 177 

Patents, list of . . . 227 

Peach black .... 28 

Peerless black . . . . 153 

Pencil for copying . . . 190 

marking . . 205 

writing on 

glass . . . 223 

Penicillium glaucum . 67 

Pens, action of ink on . 123 
Permanent blue . . .115 

inks 212 

Persian berries . . . 114 

red . . . . . , . 176 

Photographic detection 

of forgery . . . 131 
examination of 

writing .... 1 30 

reproduction of 

coloured objects . 179 

Piedmontese galls . . 45 
Pigments, black, for 

printing . . . 151 
for trichromatic 

printing . . . 182 

peculiarities of . . 172 

permanency of . . 172 

pure . .. ... 181 

Pink madder .. V .- . 176 

Pistachio galls ... 48 
Platinum in fireproof 

inks 226 

in marking inks . . 204 

Poison ivy . . . . . 196 

oak. . .. ... . 196 

sumach . . . . 198 

Poppy juice . . . . 198 

Printed books . . . . 134 

Printing . . , . . .132 
different colours in 

one impression . 240 

inks . . . -....' 132 

coloured s .167 



INDEX 



249 



Printing, inks early 
methods of 
manufacture 136 
modern 

methods of 
manufacture 139 
patent . . . 234 
Process work . . . . 169 
Procter's method of es- 
timating tannin . . 80 
Protocatechuic acid . . 74 
Provisional colour in 

marking inks 199 

in writing inks 93 

Prussian blue . . . 115, 176 

" Pulp " of printing ink 162 

Purple ink . . . .112,114 

madder . . . 115, 176 

pigments for printing 

inks 177 

Purpurine 175 

Pyrocatechin .... 74 
Pyrogallol . . . . 72, 74 

QUACK'S mixing machine 161 

Quebracho tannin . . 52 

Quercetrin 57 

Quercitannic acid . . 66 

RAW Sienna . . .115,175 

Red galls 48 

pigments . . .115, 175 

printing ink . . . 175 

writing inks 112, 113, 117 

Redwood's marking ink 199 

Resin inks for glass . . 223 

Resinous safety inks . 208 

Resorcin ink . . . . 128 

Rhus copallina ... 56 

coriaria .... 55 

cotinus .... 56 

glabra 56 

radicans . . . . 198 
toxicodendron . . 196 



Rhus venenata . . . 198 

vernicia . . . . 198 

Roman ochre . . . . 175 

Rose madder . . . 1 1 5 , 1 76 

Rubber stamp inks . . 222 

Rubrics . . . . . . 112 

Rufigallic ink .... 50 

Runge's chrome ink . . 106 

SAFETY inks .... 207 
papers . . . . 210, 212 
Sauer's apparatus . . 147 
Scheele's green . . . 177 
Screens for colour print- 
ing . 1 80 

Semecarpus anacardium 193 

Sepia 7, 15 

British .... 22 
chemical composi- 
tion of .... 19 
examination of . . 22 

fossil 17 

ink of 17 

manufacture of . . 1 8 
permanency of . 23,115 

Sepiaic acid .... 21 
Shale blacks . . 153,158 

Show-card ink . . . . 222 

Sicilian sumach ... 57 

Silicate of carbon . . 153 

Silver inks 113 

marking inks . . 199 

writing on ... 224 

Sizing, destruction of . 1 30 

Sloe juice 198 

Soluble glass ink . . . 209 

Spanish black .... 28 

Stability of writing inks 123 

Steam-heated kettles . 146 

Stencil inks 222 

Stripe test for inks . . 121 
Stylographic ink . . 13, in 

Sumach 55 

ink from .... 57 
R 



250 



INDEX 



Sumach, tannin of . 51,56 
Superheated steam for 

boiling oils . . . . 148 

Sympathetic inks . 8, 214 

patent . . . 216 

TAMARIX galls .... 48 

Tannates of iron . . 76, 78 

Tannin in oak barks . . 65 

determination of 80, 84 

Tannins 49 

chestnut .... 53 
classification of . 50 

composition of . . 51 
divi-divi .... 58 
in galls . . 39,43,48 
iron-blueing . . 50, 52 
iron-greening . . 51 
myrobalans ... 60 
oak-bark . . . 52, 63 
reactions of ... 50 
suitability for ink . 52 
sumach . . . .56 
valonia .... 62 
Terebinth galls . . . 49 

Terminalia 59 

Thenius' lampblack fur- 
nace 152 

Three-colour printing . 178 
Tin, inks for writing on 224 
" Tinctogen " grouping 73 
Tormentilla tannin . . 51 
Toxicodendric acid . . 197 
Traill's safety ink . . 209 
Transparent alumina . 182 
Trichromatic printing . 178 

prints 182 

Tungstic acid in inks . 109 
Turkey red . . . . 176 

ULTRAMARINE 115, 176, 182 
Umber in printing inks . 178 
Unoxidised iron-gall 
inks 94 



VALONIA 60 

ink from .... 62 

tannin of . . . . 62 

Vanadium, reactions of . no 

inks . . 75, 109, 128 

yellow 174 

Vandyke brown . . . 115 

Varnish, composition of 145 

manufacture of . . 141 

mixing . . . . 160 

varieties of . . . 145 

Vegetable inks . . . 192 

Vellum manuscripts . 10 

Vermilion . .. 115, 175, 182 

Viedt's copper logwood 

ink 105 

Vine black 28 

Violet aniline ink . . . 117 

black ink . . . . 104 

inks 114 

Vogel's photographic 

plates 179 



WAX tablets . 
White galls . 

inks . . 

lead . . 

pigments . 



3 

38 
1/4,213 

174 

174 



Wittstein's iron tan- 
nates .... 76, 89 
Wood, inks for writing on 

on 225 

Writing, differentiation 

of ..... 128 
examination of . . 124 
falsification of . . 126 
photographic ex- 
amination of . . 130 
progress of ... 2 
restoration of . . 125 
Writing inks 

" Alizarine " 13, 94 
aniline . . 13, 115 
carbonaceous . 34 



INDEX 



251 



Writing inks, coloured . 


112 


Writing tablets . . . 


4 


composition of 


I 2O 






examination of 


119 






gallic acid . . 


9 6 


YELI,OW aniline inks 


117 


iron -gall . . 


86 


inks . . . .112, 


114 


Japan . . 98, 


121 


lake 


174 


logwood 


103 


madder .... 


174 


manufacture 




ochre . . . 115, 


175 


of .... 


87 


pigments 115, 174, 


182 


oxidised . . 


9 2 






tests for . . 


119 






unoxidised 


94 


ZINC labels, ink for . . 


224 


vanadium, 


75, 


white 


174 


109, 


128 







Printed by BALLANTYNE, HANSON 
London &* Edinburgh 



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